OFFSET
1,1
COMMENTS
The number of partitions of k into prime parts smaller than itself gives the number of times that a(n) = k. - Gionata Neri, Jun 11 2015
That number of partitions is A000607(k) if k is not prime, and A000607(k) - 1 if k is prime. - Robert Israel, Jun 11 2015
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(31)=25 because 46 = 2 * 23 and 25 = 2 + 23.
MAPLE
count:= 0:
for n from 2 while count < 200 do
if not isprime(n) then
count:= count+1;
a[count]:= add(t[1]*t[2], t=ifactors(n)[2])
fi
od:
seq(a[i], i=1..count); # Robert Israel, Jun 11 2015
MATHEMATICA
Total@ Flatten[Table[#1, {#2}] & @@@ FactorInteger@ #] & /@ Select[Range@ 120, CompositeQ] (* Michael De Vlieger, Jun 11 2015 *)
t = {}; Do[If[! PrimeQ[n], AppendTo[t, Apply[Dot, Transpose[FactorInteger[n]]]]], {n, 4, 245}]; t (* Zak Seidov, Jul 03 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Patrick De Geest, Jun 15 1998
STATUS
approved