A249730 Odd nonprime terms in A250251.

1, 9, 15, 25, 35, 49, 77, 121, 143, 147, 153, 169, 221, 289, 323, 361, 437, 529, 667, 841, 899, 961, 1147, 1369, 1517, 1681, 1763, 1849, 2021, 2209, 2491, 2809, 3127, 3481, 3599

Offset

1,2

Comments

This sequence lists the numbers which together with all their multiples with the powers of 2 give the starting values for the prime recurrences whose union is A250251, the fixed points of permutations A250249 and A250250.

After 1, contains the terms from columns 2 and 3 of the Sieve of Eratosthenes: A083140 (A083221), but only from those rows r for which A055396(r) (the index of smallest dividing prime r) is fixed by A250249 and A250250, i.e., is in A250251. The first r for which this is not the case is 73, which is in A249729 instead. However, because there are infinitely many primes in A250251, and especially because 2 and 3 are among them, this sequence is infinite.

Links

Table of n, a(n) for n=1..35.

Prog

(Scheme, with Antti Karttunen's IntSeq-library)
(define A249730 (MATCHING-POS 1 1 (lambda (n) (and (odd? n) (not (prime? n)) (= n (A250249 n))))))

Crossrefs

Subsequence of A250251.

Cf. A083140, A083221, A249821, A250249, A250250.

Sequence in context: A227198 A279102 A319529 * A342418 A251415 A109888

Adjacent sequences: A249727 A249728 A249729 * A249731 A249732 A249733

Keyword

nonn

Author

Antti Karttunen, Nov 18 2014

Status

approved