A290348 Denominators of the Harary index for the n-halved cube graph.

1, 1, 1, 1, 1, 3, 3, 3, 1, 5, 5, 15, 15, 105, 105, 105, 105, 315, 315, 315, 315, 3465, 3465, 3465, 693, 9009, 3003, 3003, 3003, 5005, 5005, 5005, 5005, 85085, 17017, 153153, 153153, 2909907, 2909907, 14549535

Offset

1,6

Links

Table of n, a(n) for n=1..40.

Eric Weisstein's World of Mathematics, Halved Cube Graph

Eric Weisstein's World of Mathematics, Hypercube Graph

Example

First few terms are 0, 1, 6, 26, 100, 1096/3, 3920/3, 13936/3, 16544, 296256/5, ....

Mathematica

Table[-2^(n - 1) HarmonicNumber[n] - 2^(2 n - 1) Re[LerchPhi[2, 1, n + 1]], {n, 20}] // Denominator

Crossrefs

Cf. A290347 (numerators).

Sequence in context: A201277 A163644 A339901 * A014465 A226645 A243095

Adjacent sequences: A290345 A290346 A290347 * A290349 A290350 A290351

Keyword

nonn,frac

Author

Eric W. Weisstein, Jul 28 2017

Status

approved