A260439 Column index to A255551: a(1) = 0; for n > 1: if n is Lucky number then a(n) = 1, otherwise for a(2k) = k, and for odd unlucky numbers, a(n) = 1 + the position at the stage where n is removed in the Lucky sieve.

0, 1, 1, 2, 2, 3, 1, 4, 1, 5, 3, 6, 1, 7, 1, 8, 4, 9, 2, 10, 1, 11, 5, 12, 1, 13, 2, 14, 6, 15, 1, 16, 1, 17, 7, 18, 1, 19, 3, 20, 8, 21, 1, 22, 2, 23, 9, 24, 1, 25, 1, 26, 10, 27, 2, 28, 3, 29, 11, 30, 4, 31, 1, 32, 12, 33, 1, 34, 1, 35, 13, 36, 1, 37, 1, 38, 14, 39, 1, 40, 5, 41, 15, 42, 2, 43, 1, 44, 16, 45, 4, 46, 1, 47, 17, 48, 3, 49, 1, 50, 18, 51, 6, 52, 1

Offset: 1

Author

Antti Karttunen, Jul 29 2015

Keywords

• nonn

Comments

a(1) = 0, because 1 is outside of A255551 array proper.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10003

Crossrefs

Cf. A000959, A050505, A145649, A255543, A255551.

Cf. also A260438 (corresponding row index).

Cf. A078898, A246277, A260429, A260437, A260739 for column indices to other arrays similar to A255551.

Programs

Scheme

(define (A260439 n) (cond ((= 1 n) 0) ((not (zero? (A145649 n))) 1) ((even? n) (/ n 2)) (else (let searchrow ((row 2)) (let searchcol ((col 1)) (cond ((>= (A255543bi row col) n) (if (= (A255543bi row col) n) (+ 1 col) (searchrow (+ 1 row)))) (else (searchcol (+ 1 col))))))))) ;; Code for A255543bi given in A255543.

Formula

Other identities. For all n >= 1:

a(2n) = n.

Also, for all n >= 2:

A255551(A260438(n), a(n)) = n.

a(A219178(n)) = 2.