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A056641 Least positive integer k for which (b+1)^k is not palindromic in base b, b = 2, 3, 4, ... 0

%I

%S 4,3,4,4,4,5,5,5,5,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,

%T 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,

%U 8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9

%N Least positive integer k for which (b+1)^k is not palindromic in base b, b = 2, 3, 4, ...

%C Sequence of run lengths is C(n,[ (n-1)/2 ]) (= A037952), n=1,2,3,...; sequence of b where a(b) != a(b-1), b >= 3, is C(b-1,[ (b-1)/2 ]) (= A001405).

%e The 4th term is 4 because base 5 representations of (5+1)^1 = 11, (5+1)^2 = 121, (5+1)^3 = 1331, are all palindromic, while (5+1)^4 = 20141 is not.

%t palq[x_] := x == Reverse[x] Table[x = 0; While[palq[IntegerDigits[(t + 1)^x, t]], ++x]; x, {t, START, FINISH}] (* _Dylan Hamilton_, Aug 15 2010 *)

%Y Cf. A037952, A001405.

%K nonn,base

%O 2,1

%A Helge Robitzsch (hrobi(AT)math.uni-goettingen.de), Aug 11 2000

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Last modified May 19 17:44 EDT 2022. Contains 353847 sequences. (Running on oeis4.)