A032284 "DIK" (bracelet, indistinct, unlabeled) transform of 3,3,3,3...

3, 9, 22, 57, 150, 444, 1362, 4497, 15338, 54018, 193722, 705392, 2593398, 9612144, 35840622, 134318097, 505486878, 1909275084, 7234415562, 27489389850, 104718539638, 399828796884, 1529767891122, 5864087533072, 22518048468582, 86607787095594, 333600173734122

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

C. G. Bower, Transforms (2)

Index entries for sequences related to bracelets

Formula

G.f.: (3*x/((1-x)*(1-2*x)) + Sum_{d>0} phi(d)*log((1-x^d)/(1-4*x^d))/d)/2. - Andrew Howroyd, Jun 20 2018

Prog

(PARI) seq(n)={Vec(3*x/((1-x)*(1-2*x)) + sum(d=1, n, eulerphi(d)/d*log((1-x^d)/(1-4*x^d) + O(x*x^n))))/2} \\ Andrew Howroyd, Jun 20 2018

Crossrefs

Cf. A032283.

Sequence in context: A354648 A192663 A114697 * A329163 A296582 A203454

Adjacent sequences: A032281 A032282 A032283 * A032285 A032286 A032287

Keyword

nonn

Author

Christian G. Bower

Extensions

Terms a(24) and beyond from Andrew Howroyd, Jun 20 2018

Status

approved