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%I #18 Jul 16 2021 20:01:00
%S 21,1066338805156287287067,1124161332414632881704,
%T 2305867155177711644802,2306166776784312535170,5744341611556736174883
%N Decimal numbers k such that there is some base b such that (k regarded as a base-b number) = (1/b)*(k regarded as a base-10 number).
%e 21_3 = 7 = 21/3, so 21 is a term.
%e 30 is not a term because the base b would be 5 with 30_5 = 15, but 30 is not 5*15.
%o (PARI) isok(n) = {my (d = digits(n)); for (b=vecmax(d)+1, max(9, vecmax(d)-1), if (n == b*fromdigits(d, b), return (1));); return (0);} \\ _Michel Marcus_, Dec 11 2017
%Y Subsequence of A062010.
%K base,fini,full,nice,nonn
%O 1,1
%A _Erich Friedman_, Jun 27 2001
%E Name corrected by _Michel Marcus_, Dec 11 2017
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