A256990 One-based row index of n in array A256995.

0, 1, 1, 1, 2, 3, 1, 2, 4, 3, 1, 5, 6, 7, 2, 4, 8, 3, 1, 9, 10, 5, 6, 11, 7, 2, 12, 13, 14, 15, 4, 8, 16, 3, 1, 17, 18, 9, 10, 19, 5, 6, 20, 21, 22, 11, 7, 23, 2, 12, 24, 25, 13, 14, 26, 15, 4, 27, 28, 29, 30, 31, 8, 16, 32, 3, 1, 33, 34, 17, 18, 35, 9, 10, 36, 37, 38, 19, 5, 39, 6, 20, 40, 41, 21, 22, 42, 11, 7

Offset

1,5

Comments

Also one-based column index for array A256997.

a(1) = 0 by convention, as 1 is outside of the actual arrays A256995 & A256997.

Links

Antti Karttunen, Table of n, a(n) for n = 1..8192

Formula

a(1) = 0; for n > 1, if A213714(n) = 0 [i.e., if n is one of the terms of A055938], then a(n) = A234017(n), otherwise a(n) = a(A213714(n)).

In other words, a(1) = 0, and for n > 1, if n = A055938(k) for some k, then a(n) = k, otherwise it must be that n = A005187(h) for some h, in which case a(n) = a(h).

Prog

(Scheme, with memoization-macro definec)
(definec (A256990 n) (cond ((= 1 n) 0) ((zero? (A213714 n)) (A234017 n)) (else (A256990 (A213714 n)))))

Crossrefs

Cf. A005187, A055938, A213714, A234017, A256995, A256997.

Cf. A256989 (corresponding column index), A255560.

Sequence in context: A279345 A097966 A177993 * A071503 A029271 A035459

Adjacent sequences: A256987 A256988 A256989 * A256991 A256992 A256993

Keyword

nonn

Author

Antti Karttunen, Apr 14 2015

Status

approved