cp's OEIS Frontend

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.

A323603 Smallest b > 1 not already in the sequence such that b^(c-1) == 1 (mod c^2), i.e., c is a base-b "Wieferich pseudoprime", where c is the n-th composite number (A002808).

This page as a plain text file.
%I A323603 #5 Jan 19 2019 23:21:54
%S A323603 17,37,65,80,101,145,197,26,257,325,401,244,485,577,182,677,728,177,
%T A323603 901,1025,604,1157,99,1297,1445,170,1601,1765,1937,82,2117,2305,1047,
%U A323603 2501,2024,529,2917,1451,3137,721,3365,3601,3845,3725,4097,168,1945,4625,530
%N A323603 Smallest b > 1 not already in the sequence such that b^(c-1) == 1 (mod c^2), i.e., c is a base-b "Wieferich pseudoprime", where c is the n-th composite number (A002808).
%C A323603 First differs from A256517 at n = 12.
%C A323603 Is this a permutation of the positive integers > 1?
%o A323603 (PARI) my(v=vector(1)); forcomposite(c=1, 50, my(b=2); while(Mod(b, c^2)^(c-1)!=1, b++; if(Mod(b, c^2)^(c-1)==1, for(k=1, #v, if(b==v[k], b++)))); v=concat(v, b); print1(v[#v], ", "))
%Y A323603 Cf. A002808, A256517, A323602.
%K A323603 nonn
%O A323603 1,1
%A A323603 _Felix Fröhlich_, Jan 19 2019