A184273 Number of distinct n X 2 toroidal 0..3 arrays.

10, 76, 700, 8296, 104968, 1399176, 19175140, 268447816, 3817763740, 54975738736, 799645010860, 11728126132976, 173215372864600, 2573485530115576, 38430716856090160, 576460752706084936, 8680820741074491040, 131176846752106589576, 1988364834899715824380

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Mathematica

T[n_, k_] := (1/(n*k))*Sum[Sum[EulerPhi[c]*EulerPhi[d]*4^(n*k/LCM[c, d]), {d, Divisors[k]}], {c, Divisors[n]}]; a[n_] := T[n, 2]; Array[a, 20] (* Jean-François Alcover, Oct 31 2017, after Andrew Howroyd *)

Crossrefs

Column 2 of A184277.

Sequence in context: A169584 A107903 A075489 * A185986 A225828 A000808

Adjacent sequences: A184270 A184271 A184272 * A184274 A184275 A184276

Keyword

nonn

Author

R. H. Hardin, Jan 10 2011

Extensions

Terms a(13) and beyond from Andrew Howroyd, Sep 27 2017

Status

approved