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

Offset: 1

Author

Antti Karttunen, Jul 29 2015

Keywords

• nonn

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

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.

Programs

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.

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.