A334951 a(n) is the smallest candidate for the n-th term of Recamán's sequence A005132.

0, -1, -1, 0, 2, -3, 1, 6, 12, 3, 11, 0, 10, -3, 9, -6, 8, -9, 7, 24, 42, 21, 41, 18, -6, 17, -9, 16, -12, 15, -15, 14, -18, 13, 45, 78, 42, 77, 39, 0, 38, -3, 37, -6, 36, -9, 35, -12, 34, -15, 33, -18, 32, -21, 31, -24, 30, -27, 29, -30, 28, -33, 27, -36, 26, -39, 25, 90, 156, 87, 155, 84

Offset: 0

Author

Omar E. Pol, May 17 2020

Keywords

• sign

Comments

For n > 0 and after A005132(n-1) the algorithm of Recamán's sequence first explores if a(n) is a valid number to be its next term. If a(n) is nonnegative and not already in the sequence A005132 then a(n) is accepted, so A005132(n) = a(n), otherwise a(n) is rejected and A005132(n) = A005132(n-1) + n, not a(n).

For an illustration of initial terms see the diagram in A334950.

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..10000
• Index entries for sequences related to Recamán's sequence

Crossrefs

Bisection of A334950.

Cf. A005132, A334952.

Formula

a(0) = 0; for n > 0, a(n) = A005132(n-1) - n.