OFFSET
0,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
EXAMPLE
a(7) = 7 because 7^2+1 = 2*5^2 and the sum of the 2 distinct prime divisors {2, 5} is 7.
MAPLE
with(numtheory):for n from 0 to 110 do:x:=factorset(n^2+1):n1:=nops(x):s:=0:for m from 1 to n1 do: s:=s+x[m]:od: printf(`%d, `, s):od:
MATHEMATICA
Join[{0}, Table[Total[Transpose[FactorInteger[n^2+1]][[1]]], {n, 60}]] (* Harvey P. Dale, Oct 18 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 28 2011
STATUS
approved