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A335180
Define b(n) by 1/cm(w) = Sum_{n >= 0} b(3*n)*w^(3*n), where cm(w) is the elliptic function defined in A104134; a(n) = numerator of b(3*n).
3
1, 1, 1, 23, 25, 619, 8083, 584929, 1273037, 202602551, 1543302079, 208247895067, 951782914315, 2366380533924005, 180256368687985157, 12651975031966998901, 55071424621489369589, 3670628209891560101791, 93468279611939477215967, 67638487586433857706623771
OFFSET
0,4
REFERENCES
Oscar S. Adams, Elliptic Functions Applied to Conformal World Maps, Special Publication No. 112 of the U.S. Coast and Geodetic Survey, 1925. See pp. 3-4.
EXAMPLE
1/cm(w) = 1 + (1/3)*w^3 + (1/18)*w^6 + (23/2268)*w^9 + (25/13608)*w^12 + (619/1857492)*w^15 + ...
PROG
(PARI) anum(nn) = my(A = O(x)); for(i=0, nn, A = 1 - intformal(intformal(A^2)^2)); my(v=Vec(1/A)); apply(x->numerator(x), vector(#v\3, k, v[3*k-2])); \\ Michel Marcus, Jun 10 2020
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
STATUS
approved