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%I #15 Mar 07 2015 10:19:00
%S 1,1,2,2,3,2,3,3,3,4,2,3,3,3,4,4,4,4,2,4,5,3,3,5,3,5,4,5,3,4,4,4,4,4,
%T 3,6,3,4,3,6,3,5,3,4,5,5,2,6,3,5,5,6,2,5,5,5,5,3,3,7,3,4,6,5,6,5,4,5,
%U 3,5,3,7,4,4,4,4,3,7,2,8,4,5,3,7,6,4,3
%N Number of bases (2 <= b <= n+1) in which n is a palindrome.
%C a(n) >= 1, since n will always have a single "digit" in base n+1.
%H T. D. Noe, <a href="/A126071/b126071.txt">Table of n, a(n) for n = 1..1000</a>
%e From bases 2 to 9 respectively, 8 can be represented as: 1000, 22, 20, 13, 12, 11, 10, 8. Three of those are symmetrical (22, 11, 8) and so a(8) = 3.
%t Table[cnt = 0; Do[d = IntegerDigits[n, k]; If[d == Reverse[d], cnt++], {k, 2, n + 1}]; cnt, {n, 100}] (* _T. D. Noe_, Oct 04 2012 *)
%o (PARI) a(n) = sum(k=2, n+1, d = digits(n, k); Vecrev(d) == d); \\ _Michel Marcus_, Mar 07 2015
%Y Cf. A016026.
%Y Cf. A016038, A047811 (related to numbers having 2 bases).
%K nonn,base
%O 1,3
%A _Paul Richards_, Mar 01 2007
%E Extended by _T. D. Noe_, Oct 04 2012