A331003 a(n) is the imaginary part of f(n) (as defined in A330779).

0, 1, 1, -1, -1, 2, 2, -2, -2, 2, 2, -2, -2, 3, 3, -3, -3, 2, 2, -4, -4, 3, 3, -3, -3, 4, 4, -3, -3, 4, 4, -4, -4, 4, 4, -5, -5, 3, 3, -5, -5, 5, 5, -6, -6, 3, 3, -6, -6, 4, 4, -5, -5, 5, 5, -6, -6, 6, 6, -7, -7, 3, 3, -7, -7, 5, 5, -6, -6, 5, 5, -6, -6, 5, 5

Offset

0,6

Links

Rémy Sigrist, Table of n, a(n) for n = 0..10000

Rémy Sigrist, PARI program for A331003

Formula

a(2*k+2) = a(2*k+1) for any k >= 0.

a(2*k+1) = a(2*k) + A330779(2*k+1) * (-1)^k for any k >= 0.

Prog

(PARI) See Links section.

Crossrefs

Cf. A330779.

Sequence in context: A209253 A165113 A069903 * A086007 A108582 A345378

Adjacent sequences: A331000 A331001 A331002 * A331004 A331005 A331006

Keyword

sign

Author

Rémy Sigrist, Jan 05 2020

Status

approved