%I #10 Mar 06 2019 10:08:55
%S 2,3,2,3,2,5,14,3,2,3,2,5,21,3,2,3,2,5,8,3,2,7,10,5,10,3,2,3,2,7,15,5,
%T 6,3,2,5,14,3,2,3,2,5,14,3,2,7,10,5,6,3,2,6,21,5,10,3,2,3,2,7,21,5,6,
%U 3,2,5,10,3,2,3,2,7,14,5,10,3,2,5,6,3,2,7,10,5,6,3,2,6,6,7,15,5,22,3,2,5,14
%N Smallest k such that k and k + n have the same prime signature.
%H Alois P. Heinz, <a href="/A086489/b086489.txt">Table of n, a(n) for n = 1..20000</a>
%e a(7) = 14 as 14 and 14+7 = 21 have the same prime signature p*q.
%e a(13) = 21 as 21 is the smallest number such that 21 +13 = 34 and 21 both have the same prime signature p*q.
%e a(19) = 8 as 8 +19 = 27 = 3^3,8 = 2^3 both have the prime signature p^3.
%o (PARI) ps(n) = local(f); f = factor(n); vecsort(f[,2]); a(n) = local(P, m, v); P = vector(n, i, ps(i)); m = 1; while (1, for (i = 1, n, v = ps(m*n + i); if (v == P[i], return((m - 1)*n + i), P[i] = v)); m++); \\ _David Wasserman_, Mar 09 2005
%Y Cf. A085072, A085876.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Jul 28 2003
%E More terms from _David Wasserman_, Mar 09 2005