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A070315
Third diagonal of triangle in A046739.
1
1, 21, 161, 813, 3361, 12421, 42865, 141549, 453905, 1426725, 4422913, 13579309, 41408833, 125667333, 380081105, 1146795693, 3454279345, 10392196645, 31238454241, 93845384301, 281808780641, 845996765061, 2539181475121, 7620027450733, 22865249731921
OFFSET
4,2
LINKS
D. P. Roselle, Permutations by number of rises and successions, Proc. Amer. Math. Soc., 19 (1968), 8-16.
D. P. Roselle, Permutations by number of rises and successions, Proc. Amer. Math. Soc., 19 (1968), 8-16. [Annotated scanned copy]
FORMULA
a(n) = 3^n - (3n+2)*2^(n-1) + 2n^2. - Ralf Stephan, May 09 2004
G.f.: -x^4*(12*x^5-40*x^4+39*x^3+9*x^2-11*x-1) / ((x-1)^3*(2*x-1)^2*(3*x-1)). [Colin Barker, Feb 03 2013]
PROG
(PARI) a(n) = 3^n - (3*n+2)*2^(n-1) + 2*n^2; \\ Michel Marcus, Oct 25 2017
CROSSREFS
Cf. A046739.
Sequence in context: A296832 A267473 A179097 * A242191 A146301 A338891
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 15 2002
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), Oct 01 2002
More terms from Colin Barker, Feb 03 2013
STATUS
approved