a(0) = 0; thereafter a(n) is the least integer (in absolute value) not yet in the sequence such that the absolute difference of a(n-1) and a(n) is a square; in case of a tie, preference is given to the positive value.
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published version)
COMMENTS
Conjecture: For n > 2, 16, |a(n)| is within (1/2)*sqrt(n/2) of floor(n/2). See A379071. - N. J. A. Sloane, Dec 29 2024 [Corrected by _Paolo Xausa_, Jan 21 2025]
Discussion
Mon Jan 20
22:59
OEIS Server: Installed first b-file as b380311.txt.
Recamán's sequence (or Recaman's sequence): a(0) = 0; for n > 0, a(n) = a(n-1) - n if nonnegative and not already in the sequence, otherwise a(n) = a(n-1) + n.
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published version)
Smallest prime that is the sum of 2n+1 squares of consecutive odd primes, or 0 if no such prime exists.
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published version)
A version of the array
A229607 without duplicates, read by antidiagonals: each row starts with the least prime not in a previous row, and each number p in a row is followed by the greatest prime q in the interval p < q < 2*p not in a previous row (or 0 if no such q exists).
(history;
published version)
Discussion
Mon Jan 20
22:54
OEIS Server: Installed first b-file as b380277.txt.
Square array read by antidiagonals downwards in which each row starts with the least prime not in a previous row, and each prime p in a row is followed by the greatest prime < 2*p.
(history;
published version)
Discussion
Mon Jan 20
22:53
OEIS Server: Installed first b-file as b229607.txt.
Ramanujan primes R_n: a(n) is the smallest number such that if x >= a(n), then pi(x) - pi(x/2) >= n, where pi(x) is the number of primes <= x.
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published version)
Maximal length of a factorization of n into factors > 1 all having the same sum of prime indices.
(history;
published version)
Discussion
Mon Jan 20
22:52
OEIS Server: Installed first b-file as b371733.txt.
Discussion
Mon Jan 20
22:52
OEIS Server: Installed first b-file as b359196.txt.
