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.
%I A085075 #4 Dec 05 2013 19:56:18 %S A085075 3,2,0,19,35,13,343,0,39,43,275,103,55,14,0,67,539,37,99,62,21,137, %T A085075 2375,49,51,4913,279,173,2639,61,0,65,33,34,0,73,265,38,999,163,1595, %U A085075 257,175,44,91,281,29375,0,99,203,207,211,2375,219,783,341,57,353,14399,487,123 %N A085075 Smallest number a(n) == -1 (mod n) such that the prime signature of n and a(n) is the same, or 0 if no such number exists. %e A085075 a(6) =35 = 6*6 -1 = 3*13 and 6 = 2*3 are both of prime signature p*q, where p and q are primes. %Y A085075 Cf. A085074. %K A085075 nonn %O A085075 2,1 %A A085075 _Amarnath Murthy_, Jul 01 2003 %E A085075 More terms from _David Wasserman_, Jan 12 2005