OFFSET
1,1
COMMENTS
Similar to A257367 but here the prime factors of a(n) are not considered.
Again, while in A257367 the prime numbers are not allowed because they would be just a trivial solution, here they are part of the terms of the sequence. The first one is 15752927.
Values of k are 2, 2, 3, 6, 4, 7, 5, 4, 7, 8, 11, 11, 5, 8, 11, 11, 9, 5, 9, 15, 14, 7, 9, 10, 12, 17, 19, 33, ...
Numbers tested up to 10^9.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..40
EXAMPLE
258 = 2*3*43, 259 = 7*37, 261 = 3*3*29, 262 = 2*131 and 2 + 3 + 43 + 7 + 37 + 3 + 3 + 29 + 2 + 131 = 260.
MAPLE
with(numtheory): P:= proc(q) local a, b, c, k, n;
for n from 1 to q do a:=0; k:=0; while a<n do k:=k+1;
b:=ifactors(n-k)[2]; b:=add(b[j][1]*b[j][2], j=1..nops(b));
c:=ifactors(n+k)[2]; c:=add(c[j][1]*c[j][2], j=1..nops(c));
a:=a+b+c; od; if a=n then print(n); fi; od; end: P(10^9);
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Jun 15 2017
STATUS
approved