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A100178 Structured hexagonal diamond numbers (vertex structure 5). 6
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 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

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: A171442 A093809 A037157 * A106113 A028419 A046664

Adjacent sequences:  A100175 A100176 A100177 * A100179 A100180 A100181

KEYWORD

nonn,easy

AUTHOR

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

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Last modified February 17 14:19 EST 2012. Contains 206038 sequences.