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A133923 a(1)=1, and for n>1, a(n) = a(n-1)/2, if a(n-1) is divisible by 2, otherwise a(n) = A000005(n*a(n-1)). 1

%I #8 Jan 13 2024 10:52:36

%S 1,2,1,3,4,2,1,4,2,1,2,1,2,1,4,2,1,6,3,12,6,3,4,2,1,4,2,1,2,1,2,1,4,2,

%T 1,9,6,3,6,3,4,2,1,6,3,8,4,2,1,6,3,12,6,3,8,4,2,1,2,1,2,1,6,3,8,4,2,1,

%U 4,2,1,12,6,3,9,18,9,16,8,4,2,1,2,1,4,2,1,8,4,2,1,6,3,8,4,2,1,6,3,18

%N a(1)=1, and for n>1, a(n) = a(n-1)/2, if a(n-1) is divisible by 2, otherwise a(n) = A000005(n*a(n-1)).

%C The formula could be generalized to a class of sequences as a(n)= A000005(A*a(n-1)+B) if a(n-1) is not divisible by C, else a(n)= a(n-1)/C, where A, B, C are integers. In this case we have A=n, B=0 and C=2.

%o (MIT/GNU Scheme) (define (A133923 n) (cond ((< n 2) n) ((even? (A133923 (-1+ n))) (/ (A133923 (-1+ n)) 2)) (else (A000005 (* n (A133923 (-1+ n)))))))

%Y Cf. A000005.

%K nonn

%O 1,2

%A _Ctibor O. Zizka_, Jan 07 2008

%E Edited, corrected, extended and Scheme-code added by _Antti Karttunen_, Oct 05 2009

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Last modified March 29 01:36 EDT 2024. Contains 371264 sequences. (Running on oeis4.)