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A249729 Numbers not fixed by A250249 and A250250. 5
21, 27, 33, 39, 42, 45, 51, 54, 55, 57, 63, 65, 66, 69, 73, 75, 78, 81, 84, 85, 87, 90, 91, 93, 95, 99, 102, 103, 105, 108, 110, 111, 114, 115, 117, 119, 123, 125, 126, 129, 130, 132, 133, 135, 137, 138, 141, 145, 146, 150, 155, 156, 159, 161, 162, 165, 167, 168, 170, 171, 174, 175, 177, 180, 181, 182, 183, 185, 186, 187, 189, 190, 195, 197, 198, 201 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers for which A250249(n) <> n (equally: A250250(n) <> n).

If n is a member, then 2n is also a member. If any 2n is a member, then n is also a member. If n is a member, then the n-th prime, p_n (= A000040(n)) is also a member. If p_n is a member, then its index n is also a member. Thus the sequence is completely determined by its odd nonprime terms: 21, 27, 33, 39, 45, ..., and is obtained as a union of their multiples with powers of 2, and all prime recurrences that start with those values. For example, because 21 is present, then 2*21 = 42 is also present. Furthermore, 73 = p_21 is also present, as well as 367 = p_73 as well as 181 = p_42. See also comments at A250251 and A250249.

LINKS

Table of n, a(n) for n=1..76.

PROG

(Scheme, with Antti Karttunen's IntSeq-library)

(define A249729 (MATCHING-POS 1 1 (lambda (n) (not (= n (A250249 n))))))

CROSSREFS

Complement: A250251.

Cf. A000040, A250249, A250250.

Sequence in context: A318544 A173836 A064507 * A280107 A264102 A103246

Adjacent sequences:  A249726 A249727 A249728 * A249730 A249731 A249732

KEYWORD

nonn

AUTHOR

Antti Karttunen, Nov 18 2014

STATUS

approved

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Last modified February 21 23:41 EST 2020. Contains 332113 sequences. (Running on oeis4.)