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A100230 Main diagonal of triangle A100229. 5
1, 2, 10, 35, 118, 392, 1297, 4286, 14158, 46763, 154450, 510116, 1684801, 5564522, 18378370, 60699635, 200477278, 662131472, 2186871697, 7222746566, 23855111398, 78788080763, 260219353690, 859446141836, 2838557779201 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

FORMULA

a(n) = 3*a(n-1) + a(n-2) + 3 for n>1, with a(0)=1, a(1)=2. G.f.: Sum_{n>=1} a(n)*x^n/n = log((1-x)/(1-3*x-x^2)).

PROG

(PARI) a(n)=if(n==0, 1, n*polcoeff(log((1-x)/(1-3*x-x^2)+x*O(x^n)), n))

CROSSREFS

Cf. A100228, A100229.

Equals A006497(n) - 1.

Sequence in context: A116898 A033261 A197556 * A146983 A135963 A140954

Adjacent sequences:  A100227 A100228 A100229 * A100231 A100232 A100233

KEYWORD

nonn

AUTHOR

Paul D. Hanna (pauldhanna(AT)juno.com), Nov 29 2004

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Last modified February 14 18:09 EST 2012. Contains 205663 sequences.