%I #16 Nov 19 2024 23:46:10
%S 4,9,8,25,16,49,32,81,64,121,128,169,256,625,512,289,1024,361,2048,
%T 1444,1331,529,5324,2116,2197,4232,8788,841,17576,961,7569,3844,4913,
%U 7688,19652,1369,6859,5476,12321,1681,34225,1849,15129,7396,12167,2209,46225,8836,19881
%N a(n) is the least k such that sopfr(k) - sopf(k) = n.
%H Michel Marcus, <a href="/A280286/b280286.txt">Table of n, a(n) for n = 2..500</a>
%F For p prime, a(p) = p^2 (see A001248).
%o (PARI) sopfr(n) = my(f=factor(n)); sum(j=1, #f~, f[j,1]*f[j,2]);
%o sopf(n) = my(f=factor(n)); sum(j=1, #f~, f[j,1]);
%o a(n) = {my(k = 2); while (sopfr(k) - sopf(k) != n, k++); k;}
%Y Cf. A001414 (sopfr), A008472 (sopf), A001248, A280163.
%K nonn,changed
%O 2,1
%A _Michel Marcus_, Dec 31 2016