|
| |
|
|
A130656
|
|
Interlacing n^3/2 and n^2(n + 1)/2.
|
|
1
| |
|
|
1, 4, 18, 32, 75, 108, 196, 256, 405, 500, 726, 864, 1183, 1372, 1800, 2048, 2601, 2916, 3610, 4000, 4851, 5324, 6348, 6912, 8125, 8788, 10206, 10976, 12615, 13500, 15376, 16384, 18513, 19652, 22050, 23328, 26011, 27436, 30420, 32000, 35301, 37044
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
FORMULA
| a(n) = n^2 * floor((n + 1)/2)
G.f.: x(1+3x+11x^2+5x^3+4x^4)/((1-x)^4*(1+x)^3). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 09 2008]
|
|
|
MATHEMATICA
| a[n_Integer] := n^2 * Floor[(n + 1)/2]
|
|
|
CROSSREFS
| Cf. A093005 (quadratic equivalent), A065423 (linear equivalent).
Sequence in context: A120407 A033166 A049726 * A053191 A003474 A095823
Adjacent sequences: A130653 A130654 A130655 * A130657 A130658 A130659
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Olivier GERARD (olivier.gerard(AT)gmail.com), Jun 21 2007
|
| |
|
|
