A073995 Number of strings of length n over GF(4) with trace 0 and subtrace 0.

1, 1, 7, 28, 76, 256, 1072, 4288, 16576, 65536, 262912, 1051648, 4197376, 16777216, 67121152, 268484608, 1073790976, 4294967296, 17180065792, 68720263168, 274878693376, 1099511627776, 4398049656832, 17592198627328, 70368756760576, 281474976710656, 1125899957174272, 4503599828697088, 18014398710808576

Offset

1,3

Links

Table of n, a(n) for n=1..29.

F. Ruskey Strings over GF(4) with given trace and subtrace

Formula

a(n; t, s) = a(n-1; t, s) + a(n-1; t-1, s-(t-1)) + a(n-1; t-2, s-2(t-2)) + a(n-1; t-3, s-3(t-3)) where t is the trace and s is the subtrace. Note that all operations involving operands t or s are carried out over GF(4).

G.f.: -q*(26*q^3+5*q-1-13*q^2)/[(1-2q)(1-4q)(1+4q^2)]. - Lawrence Sze, Oct 24 2004

Crossrefs

Cf. A073996, A073997, A073998, A073999, A074000.

Sequence in context: A064951 A296986 A211899 * A357694 A341986 A341067

Adjacent sequences: A073992 A073993 A073994 * A073996 A073997 A073998

Keyword

easy,nonn

Author

Frank Ruskey and Nate Kube, Aug 16 2002

Extensions

More terms from Max Alekseyev, Apr 16 2013

Status

approved