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A256990 One-based row index of n in array A256995. 7
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 (list; graph; refs; listen; history; text; internal format)
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
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. A256989 (corresponding column index), A255560.
Sequence in context: A279345 A097966 A177993 * A071503 A029271 A035459
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 14 2015
STATUS
approved

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Last modified February 22 02:05 EST 2024. Contains 370239 sequences. (Running on oeis4.)