A260438 - OEIS

A260438

Row index to A255545: If n is k-th Lucky number then a(n) = k, otherwise a(n) = number of the stage where n is removed in Lucky sieve.

1, 1, 2, 1, 2, 1, 3, 1, 4, 1, 2, 1, 5, 1, 6, 1, 2, 1, 3, 1, 7, 1, 2, 1, 8, 1, 4, 1, 2, 1, 9, 1, 10, 1, 2, 1, 11, 1, 3, 1, 2, 1, 12, 1, 5, 1, 2, 1, 13, 1, 14, 1, 2, 1, 6, 1, 4, 1, 2, 1, 3, 1, 15, 1, 2, 1, 16, 1, 17, 1, 2, 1, 18, 1, 19, 1, 2, 1, 20, 1, 3, 1, 2, 1, 7, 1, 21, 1, 2, 1, 4, 1, 22, 1, 2, 1, 5, 1, 23, 1, 2, 1, 3, 1, 24, 1, 2, 1, 8, 1, 25, 1, 2, 1, 26, 1, 6, 1, 2, 1

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OFFSET

1,3

COMMENTS

For n >= 2 this works also as a row index to array A255551 (which does not contain 1) and when restricted to unlucky numbers, A050505, also as a row index to array A255543.

LINKS

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

FORMULA

Other identities. For all n >= 1:

a(A000959(n)) = n.

a(A219178(n)) = n.

a(2n) = 1. [All even numbers are removed at the stage one of the sieve.]

a(A016969(n)) = 2.

a(A258016(n)) = 3.

a(A260440(n)) = 4.

A255545(a(n), A260429(n)) = n.

For all n >= 2, A255551(a(n), A260439(n)) = n.

PROG

(Scheme)

(define (A260438 n) (cond ((not (zero? (A145649 n))) (A109497 n)) ((even? n) 1) (else (let searchrow ((row 2)) (let searchcol ((col 1)) (cond ((>= (A255543bi row col) n) (if (= (A255543bi row col) n) row (searchrow (+ 1 row)))) (else (searchcol (+ 1 col))))))))) ;; Code for A255543bi given in A255543.

CROSSREFS

Cf. A000959, A050505, A109497, A145649, A219178, A255543, A255545, A255551.

Cf. also A260429, A260439 (corresponding column indices).

Cf. A055396, A260738 for row indices to other arrays similar to A255545.

Sequence in context: A243554 A361734 A263111 * A112197 A112198 A326850

Adjacent sequences: A260435 A260436 A260437 * A260439 A260440 A260441

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jul 29 2015

STATUS

approved