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%I #24 Nov 30 2020 22:47:53
%S 1,2,3,4,5,6,7,8,13,23,46,445,2116,15226,313725,1527465,3454446,
%T 2426472326,3066511287,102461381175475216
%N Decimal numbers n which, when converted to a lower number base, show the reversed digits of n.
%C All entries lack the digit 9, because this digit is absent in the representations in bases 2 to 9.
%C The sequence is finite because for every n > 10^22 the representation of n in a base b < 10 has more digits than the representation of n in base 10. a(20) is the last term. - _Giovanni Resta_, Aug 13 2019
%e 13 is 31 in base 4. 23 is 32 in base 7. 46 is 64 in base 7.
%e 801 is not a term since it is 1080 in base 9, so with an extra 0.
%o (PARI) isok(n) = {my(d = digits(n)); for (b=2, 9, my(rd = Vecrev(digits(n, b))); if ((#rd == #d) && fromdigits(rd) == n, return (b)););} \\ _Michel Marcus_, Aug 05 2019
%Y Cf. A034294, A090144. - _R. J. Mathar_, Jul 17 2009
%K nonn,base,fini,full
%O 1,2
%A _Claudio Meller_, Jul 06 2009
%E Keyword:base, single-digit numbers and 313725 added by _R. J. Mathar_, Jul 17 2009
%E a(16)-a(17) from _Michel Marcus_, Aug 05 2019
%E a(18)-a(19) from _Giovanni Resta_, Aug 06 2019
%E a(20) from _Giovanni Resta_, Aug 13 2019