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%I #10 Jan 15 2015 11:41:18
%S 1,3,5,15,27,39,51,63,75,85,87,99,111,123,125,135,147,159,171,183,195,
%T 205,207,209,217,219,231,243,245,255,267,279,291,303,315,325,327,329,
%U 339,351,363,365,375,387,399,411,423,435,445,447,459,471,481,483,485,495,507,519,531,543,553,555
%N a(1) = 1; thereafter, odd numbers such that A055396(n) = A001511(n-1).
%C After 1, all such odd numbers whose smallest prime factor A020639(n) = A000040(k+1), where k = A007814(n-1), the 2-adic valuation of the preceding even number.
%C Any odd number present in A253789 must be one of these terms.
%H Antti Karttunen, <a href="/A253790/b253790.txt">Table of n, a(n) for n = 1..10000</a>
%o (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o (define A253790 (MATCHING-POS 1 1 (lambda (n) (or (= 1 n) (and (odd? n) (= (A055396 n) (A001511 (- n 1))))))))
%Y Cf. A000040, A001511, A007814, A020639, A029747, A055396, A253789.
%K nonn
%O 1,2
%A _Antti Karttunen_, Jan 13 2015
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