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Partial sums of A018190.
0

%I #2 Mar 30 2012 18:40:52

%S 1,2,5,12,34,115,446,1881,8386,38472,179701,849285,4047541,19415118,

%T 93623028,453486806,2205081449,10758731196,52651373968,258365785954,

%U 1270930958357,6265738653554,30952863554094,153191072337297

%N Partial sums of A018190.

%C Partial sums of number of planar simply-connected polyhexes (or benzenoid hydrocarbons) with n hexagons. The only known primes in the partial sum are 2 and 5.

%F a(n) = SUM[i=1..n] A018190(i).

%e a(6) = 1 + 1 + 3 + 7 + 22 + 81 = 115.

%Y Cf. A000228, A002216, A018190, A038142-A038147.

%K nonn

%O 1,2

%A _Jonathan Vos Post_, Apr 22 2010