A174055 Sums of three Mersenne primes.

9, 13, 17, 21, 37, 41, 45, 65, 69, 93, 133, 137, 141, 161, 165, 189, 257, 261, 285, 381, 8197, 8201, 8205, 8225, 8229, 8253, 8321, 8325, 8349, 8445, 16385, 16389, 16413, 16509, 24573, 131077, 131081, 131085, 131105, 131109, 131133, 131201, 131205, 131229, 131325, 139265, 139269, 139293, 139389, 147453, 262145, 262149

Offset: 1

Author

Jonathan Vos Post, Mar 06 2010

Keywords

• nonn

Examples

			a(1) = 3 + 3 + 3 = 9. a(2) = 3 + 3 + 7 = 13. a(3) = 3 + 7 + 7 = 17. a(4) = 7 + 7 + 7 = 21. a(5) = 3 + 3 + 31 = 37. a(6) = 3 + 7 + 31 = 41.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..969

Crossrefs

Cf. A000668, A155877, A166484, A171251, A171252, A171253, A171254, A171255, A174056, A174057.

Programs

Maple

N:= 10^6: # to get all terms <= N
for n from 1 while numtheory:-mersenne([n]) < N do od:
S:= {seq(numtheory:-mersenne([i]),i=1..n-1)}:
sort(convert(select(`<=`,{seq(seq(seq(s+t+u,s=S),t=S),u=S)},N),list)); # Robert Israel, Mar 02 2016

Formula

A000668(i) + A000668(j) + A000668(k), with integers i,j,k not necessarily distinct. The subsequence of prime sums of three Mersenne primes is A174056.

Extensions

More terms from Max Alekseyev, Oct 15 2012

Edited by Robert Israel, Mar 02 2016