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 A055517 #3 Mar 30 2012 17:30:21 %S A055517 30,4,12,0,1,4,9,2,25,4,49,15,14,27,121,35,169,33,26,55,289,77,361,91, %T A055517 38,85,529,143,46,133,44,187,841,221,961,247,62,253,42,323,1369,217, %U A055517 74,391,1681,437,1849,403,86,493,2209 %N A055517 Largest integer k such that k | Phi(k) - d(k) + n, or 0 if no such k exists, where d() is the number of divisors. %C A055517 In the case of n = 3, the condition is satisfied for all the primes. %e A055517 for a(2), 12 | [ Phi(12) + d(12) + 2 ]. %Y A055517 Cf. A020488. %K A055517 nonn %O A055517 0,1 %A A055517 _Robert G. Wilson v_, Jul 03 2000