A269380 - OEIS

A269380

a(1) = 1, after which, for odd numbers: a(n) = A260739(n)-th number k for which A260738(k) = A260738(n)-1, and for even numbers: a(n) = a(n/2).

1, 1, 2, 1, 3, 2, 5, 1, 4, 3, 7, 2, 11, 5, 6, 1, 13, 4, 9, 3, 8, 7, 17, 2, 23, 11, 10, 5, 25, 6, 19, 1, 12, 13, 15, 4, 29, 9, 14, 3, 37, 8, 41, 7, 16, 17, 43, 2, 21, 23, 18, 11, 47, 10, 31, 5, 20, 25, 35, 6, 53, 19, 22, 1, 27, 12, 61, 13, 24, 15, 67, 4, 55, 29, 26, 9, 71, 14, 33, 3, 28, 37, 77, 8, 49, 41, 30, 7, 83, 16, 89, 17, 32, 43, 39, 2

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OFFSET

1,3

COMMENTS

For odd numbers n > 1, a(n) tells which term is on the immediately preceding row of A255127 (square array generated by Ludic sieve), in the same column where n itself is.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..33011

FORMULA

a(1) = 1; after which, for even numbers a(n) = a(n/2), and for odd numbers a(n) = A255127(A260738(n)-1, A260739(n)).

Other identities. For all n >= 1:

a(A269379(n)) = n.

PROG

(definec (A269380 n) (cond ((= 1 n) n) ((even? n) (A269380 (/ n 2))) (else (A255127bi (- (A260738 n) 1) (A260739 n))))) ;; Code for A255127bi given in A255127.

CROSSREFS

Cf. A255127, A260738, A260739.

Cf. A269172, A269355, A269357, A269382, A269386, A269388 (sequences that use this function).

Cf. also A268674, A269370.

Sequence in context: A116529 A368071 A169747 * A268674 A250470 A064989

Adjacent sequences: A269377 A269378 A269379 * A269381 A269382 A269383

KEYWORD

nonn

AUTHOR

Antti Karttunen, Mar 01 2016

STATUS

approved