A171116 a(n) is the Severi degree for curves of degree n and cogenus 6.

0, 0, 0, 105, 109781, 12597900, 302280963, 3356773532, 23599355991, 122416062018, 510681301550, 1807308075111, 5622246678741, 15761274284852, 40547443860105, 97044388890450, 218379097055159, 465931135430250, 948922558475388, 1854955331788517, 3496355565562725

Offset

1,4

Links

Table of n, a(n) for n=1..21.

Sergey Fomin and Grigory Mikhalkin, Labeled floor diagrams for plane curves, Journal of the European Mathematical Society 012.6 (2010): 1453-1496; arXiv:0906.3828 [math.AG], 2009-2010.

Index entries for linear recurrences with constant coefficients, signature (13,-78,286,-715,1287,-1716,1716,-1287,715,-286,78,-13,1).

Mathematica

a[n_ ? (#<4&)] = 0;
a[n_] := 81/80 n^12 - 243/20 n^11 - 81/20 n^10 + 8667/16 n^9 - 9297/8 n^8 - 47727/5 n^7 + 2458629/80 n^6 + 3243249/40 n^5 - 6577679/20 n^4 - 25387481/80 n^3 + 6352577/4 n^2 + 8290623/20 n - 2699706;
Table[a[n], {n, 20}] (* Andrey Zabolotskiy, May 02 2022 *)

Crossrefs

Cf. A171108.

Sequence in context: A145627 A305146 A304644 * A199100 A225217 A096150

Adjacent sequences: A171113 A171114 A171115 * A171117 A171118 A171119

Keyword

nonn,easy

Author

N. J. A. Sloane, Sep 27 2010

Extensions

Name edited, terms a(7) and beyond added by Andrey Zabolotskiy, May 02 2022

Status

approved