Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting seven doublets into the initially empty word.

A194719

Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting seven doublets into the initially empty word.

Terms

    a(0) =0a(1) =1a(2) =1716a(3) =54573a(4) =492724a(5) =2467137a(6) =8786436a(7) =25066621a(8) =61189668a(9) =133071009a(10) =264735892a(11) =490704621a(12) =858686676a(13) =1432583713a(14) =2295801444a(15) =3554870397a(16) =5343375556a(17) =7826194881a(18) =11204046708a(19) =15718346029a(20) =21656369652a(21) =29356730241a(22) =39215159236a(23) =51690598653a(24) =67311601764

External references