A100178 Structured hexagonal diamond numbers (vertex structure 5).

1, 8, 29, 72, 145, 256, 413, 624, 897, 1240, 1661, 2168, 2769, 3472, 4285, 5216, 6273, 7464, 8797, 10280, 11921, 13728, 15709, 17872, 20225, 22776, 25533, 28504, 31697, 35120, 38781, 42688, 46849, 51272, 55965, 60936, 66193, 71744, 77597, 83760, 90241, 97048, 104189

Offset

1,2

Comments

Row 1 of the convolution array A213838. [Clark Kimberling, Jul 05 2012]

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Formula

a(n) = (1/6)*(8*n^3-6*n^2+4*n).

G.f.: x*(1+4*x+3*x^2)/(1-4*x+6*x^2-4*x^3+x^4). - Colin Barker, Jan 04 2012

Prog

(Magma) [(1/6)*(8*n^3-6*n^2+4*n): n in [1..40]]; // Vincenzo Librandi, Aug 03 2011

Crossrefs

Cf. A000578 = alternate vertex; A000447 = structured diamonds; A100145 for more on structured numbers.

Sequence in context: A244244 A037157 A288115 * A106113 A362153 A299260

Adjacent sequences: A100175 A100176 A100177 * A100179 A100180 A100181

Keyword

nonn,easy

Author

James A. Record (james.record(AT)gmail.com), Nov 07 2004

Status

approved