OFFSET
1,5
COMMENTS
The sequence shows a stronger version of the Goldbach conjecture that for n > 6, n has partitions with at most three distinct primes.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
EXAMPLE
a(21)=3 as 21 = 2+19 = 3+5+13 = 3+7+11.
MATHEMATICA
a[n_] := Length@Select[IntegerPartitions[n, 3, Prime@Range@PrimePi@n],
Sort@#==Union@# &]; Array[a, 100] (* Giovanni Resta, Mar 29 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Frank M Jackson, Mar 28 2013
STATUS
approved