A076508 Expansion of 2*x*(1+4*x+8*x^2)/(1-24*x^3).

2, 8, 16, 48, 192, 384, 1152, 4608, 9216, 27648, 110592, 221184, 663552, 2654208, 5308416, 15925248, 63700992, 127401984, 382205952, 1528823808, 3057647616, 9172942848, 36691771392, 73383542784, 220150628352, 880602513408

Offset

1,1

Comments

Previous name was: 3 people at a party are saying Hello to each other. Person 2 says Hello Hello. Person 3 counts the times Hello has been said and says Hello thrice that number of times. Person 1 says Hello a number of times equal to the sum of Hello's and then it is Person 2's turn again. This is the total number of Hello's said.

Links

Table of n, a(n) for n=1..26.

Index entries for linear recurrences with constant coefficients, signature (0,0,24).

Formula

G.f.: 2*x*(1+4*x+8*x^2)/(1-24*x^3). - Colin Barker, Jun 07 2012

a(n) = 2^n*b(n-1) where b(n) = 1, 2, 2, 3, 6, 6, 9, 18, 18, 27, 54, ... (n >= 0) is A038754 with each 2nd term repeated. - R. J. Mathar, May 21 2018

Crossrefs

Partial sums of A076507.

Sequence in context: A280229 A360323 A336127 * A162584 A100243 A026523

Adjacent sequences: A076505 A076506 A076507 * A076509 A076510 A076511

Keyword

nonn,easy

Author

Jon Perry, Oct 15 2002

Status

approved