cp's OEIS Frontend

A353340 Smallest positive number k such that there are exactly n integers b with k > b > 1 where the base-b representation of k is periodic.

%I A353340 #4 Apr 14 2022 15:03:22
%S A353340 1,3,5,15,10,36,80,60,120,168,260,252,360,630,504,720,840,1512,1260,
%T A353340 1800,1680,2340,3276,3120,3360,2520,9072,7200,6300,12096,7920,5040,
%U A353340 9240,7560,20520,25920,15840,10080
%N A353340 Smallest positive number k such that there are exactly n integers b with k > b > 1 where the base-b representation of k is periodic.
%o A353340 (PARI) is(n, b) = for (w=1, oo, my (d=digits(n, b^w)); if (#d<=1, return (0), #Set(d)==1, return (1))) \\ after _Rémy Sigrist_ in A321513
%o A353340 a353339(n) = my(i=0); for(b=2, n-1, if(is(n, b), i++)); i
%o A353340 a(n) = for(k=1, oo, if(a353339(k)==n, return(k)))
%Y A353340 Cf. A353339.
%K A353340 nonn,base,more
%O A353340 0,2
%A A353340 _Felix Fröhlich_, Apr 14 2022