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%I #26 May 04 2021 02:01:21
%S 0,0,0,0,0,0,0,0,0,1,0,1,1,1,1,1,1,1,1,2,1,0,1,2,1,2,1,2,1,3,1,2,0,2,
%T 1,3,1,2,2,3,1,3,1,0,2,2,1,4,1,3,2,3,1,3,0,3,2,2,1,6,1,2,2,3,2,0,1,3,
%U 2,4,1,5,1,2,3,3,0,4,1,5,2,2,1,6,2,2,2,0,1,6,2,3,2,2,2,6,1,3,0,5,0,4,1,4,4
%N Number of non-palindromic divisors of n.
%H Indranil Ghosh, <a href="/A087991/b087991.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A000005(n) - A087990(n).
%e n=132: divisors={1,2,3,4,6,11,12,22,33,44,66,132},
%e revdivisors={1,2,3,4,6,11,21,22,33,44,66,231}, a[132]=2;
%e so two of 12 divisors of n are non-palindromic:{21,132}.
%t palQ[n_] := Reverse[x = IntegerDigits[n]] == x; Table[Count[Divisors[n], _?(! palQ[#] &)], {n, 105}] (* _Jayanta Basu_, Aug 10 2013 *)
%o (Python)
%o def ispal(n):
%o w=str(n)
%o return w==w[::-1]
%o def A087991(n):
%o s = 0
%o for i in range(1, n+1):
%o if n%i==0 and not ispal(i):
%o s+=1
%o return s
%o print([A087991(n) for n in range(1,60)]) # _Indranil Ghosh_, Feb 10 2017
%Y Cf. A087990, A062687.
%K nonn,base
%O 1,20
%A _Labos Elemer_, Oct 08 2003
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