A353707 n appears in A121216 a(n) steps earlier than expected.

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

Offset: 1

Author

N. J. A. Sloane, May 05 2022

Keywords

• sign

Comments

It appears that a positive number n appears in A121216 at about the n-th term; if in fact A121216(k) = n, then a(n) = n - k.

An equivalent definition uses the inverse to A121216: a(n) = n - A225047(n).

Examples

			A121216(8) = 11, so 11 has appeared 3 steps early, therefore a(11) = 11 - 8 = 3.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program

Crossrefs

Cf. A121216, A225047, A353706.

Programs

PARI

See Links section.