A335158 - OEIS

%I #13 Jun 11 2020 03:17:20

%S 1,6,252,4536,2476656,3714984,35574686784,15246294336,582713369521920,

%T 1123804355506560,2048470579217357568,35116638500868986880,

%U 283061106066827553906954240,4665842407694959679784960,1533625072670071687067878072320,394360732972304148103168647168

%N Define b(n) by 1/sm(w) = Sum_{n >= 0} b(3*n-1)*w^(3*n-1), where sm(w) is the elliptic function defined in A104133; a(n) = denominator of b(3*n-1).

%D 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.

%e 1/sm(w) = w^(-1) + (1/6)*w^2 - (1/252)*w^5 - (1/4536)*w^8 + (11/2476656)*w^11 + (1/3714984)*w^14 - (193/35574686784)*w^17 - (5/15246294336)*w^20 + (3851/582713369521920)*w^23 + (449/1123804355506560)*w^26 - ...

%o (PARI) aden(nn) = my(A = O(x)); for(i=0, nn, A = intformal( (1 - intformal(A^2))^2) ); my(v=Vec(1/A)); apply(x->denominator(x), vector(#v\3, k, v[3*k-2]));

%Y Cf. A104133 (sm), A104134 (cm), A335157 (numerators).

%Y See also A335180, A335181.

%K nonn,frac

%O 0,2

%A _Michel Marcus_ and _N. J. A. Sloane_, Jun 08 2020