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A179937 a(n) is the product of the non-palindromic divisors of n. 2

%I #23 May 15 2023 18:14:24

%S 1,1,1,1,1,1,1,1,1,10,1,12,13,14,15,16,17,18,19,200,21,1,23,288,25,

%T 338,27,392,29,4500,31,512,1,578,35,7776,37,722,507,8000,41,12348,43,

%U 1,675,1058,47,221184,49,12500,867,17576,53,26244,1,21952,1083,1682,59

%N a(n) is the product of the non-palindromic divisors of n.

%H Indranil Ghosh, <a href="/A179937/b179937.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007955(n) / A184392(n).

%e For n = 20, set of non-palindromic divisors is {10, 20}; a(12) = 10*20 = 200.

%t Table[Times@@Select[Divisors[n],!PalindromeQ[#]&],{n,60}] (* _Harvey P. Dale_, May 15 2023 *)

%o (Python)

%o def ispal(n):

%o return n==int(str(n)[::-1])

%o def A179937(n):

%o s=1

%o for i in range(1, n+1):

%o if n%i==0 and not ispal(i):

%o s*=i

%o return s # _Indranil Ghosh_, Feb 10 2017

%Y Cf. A087990, A087991, A088000, A088001, A184392.

%K nonn,base

%O 1,10

%A _Jaroslav Krizek_, Jan 12 2011

%E More terms from _Indranil Ghosh_, Feb 10 2017

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Last modified April 19 15:34 EDT 2024. Contains 371794 sequences. (Running on oeis4.)