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A007613 (8^n + 2(-1)^n )/3.
(Formerly M2129)
+0
4
1, 2, 22, 170, 1366, 10922, 87382, 699050, 5592406, 44739242, 357913942, 2863311530, 22906492246, 183251937962, 1466015503702, 11728124029610, 93824992236886, 750599937895082, 6004799503160662, 48038396025285290 (list; graph; listen)
OFFSET

0,2

COMMENT

Equals row sums of triangle A139459(n+1). Example: 170 = (1 + 84 + 84 + 1). Triangle A139459 = the ConvOffsStoT transform of the dodecahedral numbers, A006560. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Apr 22 2008

REFERENCES

D. S. Clark, Proof without words, Math. Mag., 63 (1990), 29.

FORMULA

a(n)=A078008(3n) - Paul Barry (pbarry(AT)wit.ie), Nov 29 2003

a(n)=(A082311(n)+(-1)^n)/2=(A001045(3n+1)+(-1)^n)/2. - Paul Barry (pbarry(AT)wit.ie), Mar 24 2004

a(n)=sum{k=0..n, binomial(3n, 3k)}; - Paul Barry (pbarry(AT)wit.ie), Jan 13 2005

a(n)=8a(n-1)+6*(-1)^n. - Paul Curtz (bpcrtz(AT)free.fr), Nov 19 2007

CROSSREFS

Adjacent sequences: A007610 A007611 A007612 this_sequence A007614 A007615 A007616

Sequence in context: A123960 A091169 A000184 this_sequence A043037 A058441 A037567

Cf. A006560, A139459.

KEYWORD

nonn,easy,new

AUTHOR

njas, Robert G. Wilson v (rgwv(AT)rgwv.com)

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Last modified May 11 10:28 EDT 2008. Contains 139662 sequences.


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