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%I #18 Aug 21 2021 19:57:17
%S 21,42,51,52,54,57,63,81,84,210,231,270,297,420,462,510,520,521,522,
%T 528,540,561,570,572,573,594,610,630,693,810,840,861,891,2100,2121,
%U 2178,2300,2310,2331,2530,2541,2700,2727,2751,2961,2970,2997,4032,4200,4242
%N Numbers k such that k divided by the number constructed from a decimal point followed by the reversed digits of k is an integer, but not a power of ten.
%C Quotients equal to a power of 10 are excluded to eliminate trivial cases, e.g., 777/.777 = 1000.
%C If k is in this sequence, so is 10*k. However, 10*k can be in this sequence even if k is not (e.g., 270 is in the sequence even though 27 is not). - _Nathaniel Johnston_, Jun 23 2011
%H Nathaniel Johnston, <a href="/A192130/b192130.txt">Table of n, a(n) for n = 1..750</a>
%e a(1) = 21 because 21/.12 = 175;
%e a(6) = 57 because 57/.75 = 76.
%p isA192130 := proc(n) local d,m: d:=convert(n,base,10): m:=n/add(d[j]*10^(-j),j=1..nops(d)): return `if`(type(m,integer) and not type(simplify(log[10](m)),integer), n, NULL): end: seq(isA192130(n),n=1..4410); # _Nathaniel Johnston_, Jun 23 2011
%t revRec[n_, b_:10] := FromDigits[Reverse[IntegerDigits[n, b]]]/b^Length[IntegerDigits[n, b]]; Select[Range[3000], IntegerQ[#/revRec[#]] && Not[IntegerQ[Log[10, #/revRec[#]]]] &] (* _Alonso del Arte_, Jun 23 2011 *)
%K nonn,base
%O 1,1
%A _Gil Broussard_, Jun 23 2011