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a(n) = (A266419(n) - 1) / 2; numbers n such that 2n+1 is a nonludic number (in A192607).
5

%I #7 Jan 30 2016 03:10:11

%S 4,7,9,10,13,15,16,17,19,22,24,25,27,28,29,31,32,34,36,37,39,40,42,43,

%T 46,47,49,50,51,52,54,55,56,58,61,62,64,66,67,68,69,70,72,73,75,76,77,

%U 79,81,82,83,84,85,88,91,92,93,94,95,97,98,99,100,101,102,103,106,107,108,109,112,114,115,118,120,121

%N a(n) = (A266419(n) - 1) / 2; numbers n such that 2n+1 is a nonludic number (in A192607).

%C Odd nonludic numbers (A266419) decremented by one, then halved.

%H Antti Karttunen, <a href="/A266410/b266410.txt">Table of n, a(n) for n = 1..10220</a>

%F a(n) = (A266419(n) - 1) / 2.

%o (Scheme, with _Antti Karttunen_'s IntSeq-library)

%o (define (A266410 n) (/ (- (A266419 n) 1) 2))

%o (define A266410 (ZERO-POS 1 1 (lambda (n) (A192490 (+ n n 1)))))

%Y Complement: A266409.

%Y Cf. A192490, A192607, A266419.

%Y Cf. permutations A266418, A266638.

%Y Cf. also A047845.

%K nonn

%O 1,1

%A _Antti Karttunen_, Jan 28 2016