This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
a(7) = 1766488 = 12365416/7, where 12365416 is the concatenation of first seven terms of A100769.
spi[{ctn_,n_,a_}]:=Module[{k=1},While[Mod[ctn*10^IntegerLength[k]+k,n+1] != 0,k++];{ctn*10^IntegerLength[k]+k,n+1,k}]; NestList[spi,{1,1,1},80][[All,3]] (* Harvey P. Dale, Nov 30 2022 *)
num = 1; print(1); for (n = 2, 9, c = 10*num%n; d = n - c; print(d); num = 10*num + d); for (n = 10, 90, c = 10*num%n; d = n - c; if (d < 10, print(d); num = 10*num + d, c = 100*num%n; d = n - c; if (d < 10, d = d + n); print(d); num = 100*num + d));
Concatenation of a(0),...,a(6) is 1024569, not used so far are 3, 7, 8, 10, 11, 12, ..., the smallest of these that appended to 1024569 gives a multiple of 8 is 12: 102456912 = 8*12807114, hence a(7) = 12.
Comments