Number of ways to color vertices of a heptagon using <= n colors, allowing only rotations.

Terms

a(0) =0a(1) =1a(2) =20a(3) =315a(4) =2344a(5) =11165a(6) =39996a(7) =117655a(8) =299600a(9) =683289a(10) =1428580a(11) =2783891a(12) =5118840a(13) =8964085a(14) =15059084a(15) =24408495a(16) =38347936a(17) =58619825a(18) =87460020a(19) =127695979a(20) =182857160a(21) =257298381a(22) =356336860a(23) =486403655a(24) =655210224a(25) =871930825a(26) =1147401476a(27) =1494336195a(28) =1927561240