The On-Line Encyclopedia of Integer Sequences (OEIS)

A260439 revision #12

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

COMMENTS

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

LINKS

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

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.

PROG

(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.

CROSSREFS

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

Cf. also A260438 (corresponding row index).

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

Sequence in context: A339526 A072078 A322316 * A182471 A078378 A141197

Adjacent sequences: A260436 A260437 A260438 * A260440 A260441 A260442

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jul 29 2015

STATUS

proposed