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 A029961 Palindromic in bases 4 and 10. 40
 0, 1, 2, 3, 5, 55, 373, 393, 666, 787, 939, 7997, 53235, 55255, 55655, 57675, 506605, 1801081, 2215122, 3826283, 3866683, 5051505, 5226225, 5259525, 5297925, 5614165, 5679765, 53822835, 623010326, 954656459, 51717171715 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Robert G. Wilson v, Table of n, a(n) for n = 1..56 P. De Geest, Palindromic numbers beyond base 10 MATHEMATICA NextPalindrome[n_] := Block[{l = Floor[ Log[10, n] + 1], idn = IntegerDigits[n]}, If[ Union[idn] == {9}, Return[n + 2], If[l < 2, Return[n + 1], If[ FromDigits[ Reverse[ Take[idn, Ceiling[l/2]] ]] FromDigits[ Take[idn, -Ceiling[l/2]]], FromDigits[ Join[ Take[idn, Ceiling[l/2]], Reverse[ Take[idn, Floor[l/2]] ]]], idfhn = FromDigits[ Take[idn, Ceiling[l/2]]] + 1; idp = FromDigits[ Join[ IntegerDigits[idfhn], Drop[ Reverse[ IntegerDigits[idfhn]], Mod[l, 2]] ]]] ]]]; palQ[n_Integer, base_Integer] := Block[{idn = IntegerDigits[n, base]}, idn == Reverse[idn]]; l = {0}; a = 0; Do[a = NextPalindrome[a]; If[ palQ[a, 4], AppendTo[l, a]], {n, 1000000}]; l (* Robert G. Wilson v, Sep 30 2004 *) Select[Range[0, 10^5], PalindromeQ[#] && # == IntegerReverse[#, 4] &] (* Robert Price, Nov 09 2019 *) CROSSREFS Cf. A007632, A007633, A029962, A029963, A029964, A029804, A029965, A029966, A029967, A029968, A029969, A029970, A029731, A097855, A099165. Sequence in context: A114370 A114725 A136340 * A083665 A214752 A238201 Adjacent sequences:  A029958 A029959 A029960 * A029962 A029963 A029964 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified December 8 17:36 EST 2019. Contains 329865 sequences. (Running on oeis4.)