OFFSET
1,3
COMMENTS
a(n) gives the number of times 2*n occurs in A061228.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
EXAMPLE
MATHEMATICA
f[n_] := Select[First /@ FactorInteger[2 n], FactorInteger[2 n - #][[1, 1]] == # &]; Length /@ Table[f@ n, {n, 2, 105}] (* Michael De Vlieger, Oct 22 2015 *)
PROG
(PARI) a(n) = {my(f=factor(2*n)); sum(k=1, #f~, p=f[k, 1]; p == factor(2*n-p)[1, 1]); } \\ Michel Marcus, Oct 31 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Gionata Neri, Oct 21 2015
STATUS
approved