OFFSET
2,1
COMMENTS
This sequence satisfies a recurrence relation of order 243.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 2..361
S. N. Perepechko, The number of perfect matchings on C_m X C_n graphs, (in Russian), Information Processes, 2016, V. 16, No. 4, pp. 333-361.
S. N. Perepechko, Counting Near-Perfect Matchings on C_m × C_n Tori of Odd Order in the Maple System, Programming and Computer Software, 45(2019), 65-72.
Sergey Perepechko, Generating function in Maple notation.
FORMULA
a(n) = sqrt( Product_{j=1..n} Product_{k=1..11} (4*sin((2*j-1)*Pi/(2*n))^2 + 4*sin((2*k-1)*Pi/11)^2) ). - Seiichi Manyama, Feb 14 2021
PROG
(PARI) default(realprecision, 120);
a(n) = round(sqrt(prod(j=1, n, prod(k=1, 11, 4*sin((2*j-1)*Pi/(2*n))^2+4*sin((2*k-1)*Pi/11)^2)))); \\ Seiichi Manyama, Feb 14 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Sergey Perepechko, Jul 04 2019
STATUS
approved