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A061801
a(n) = (7*6^n - 2)/5.
10
1, 8, 50, 302, 1814, 10886, 65318, 391910, 2351462, 14108774, 84652646, 507915878, 3047495270, 18284971622, 109709829734, 658258978406, 3949553870438, 23697323222630, 142183939335782, 853103636014694
OFFSET
0,2
COMMENTS
Sum of n-th row of triangle of powers of 6: 1; 1 6 1; 1 6 36 6 1; 1 6 36 216 36 6 1; ....
LINKS
FORMULA
G.f.: (1+x)/(1-6*x)/(1-x) [Zerinvary Lajos, Jan 11 2009]
a(n) = 6*a(n-1) + 2, a(0) = 1. - Philippe Deléham, Feb 23 2014
a(n) = Sum_{k=0..n} A112468(n,k)*7^k. - Philippe Deléham, Feb 23 2014
EXAMPLE
a(2) = 50 = 1 + 6 + 36 + 6 + 1.
G.f. = 1 + 8*x + 50*x^2 + 302*x^3 + 1814*x^4 + 10886*x^5 + 65318*x^6 + ...
MAPLE
restart:g:=(1+x)/(1-6*x)/(1-x): gser:=series(g, x=0, 43): seq(coeff(gser, x, n), n=0..30); # Zerinvary Lajos, Jan 11 2009
PROG
(PARI) { for (n=0, 200, write("b061801.txt", n, " ", (7*6^n - 2)/5) ) } \\ Harry J. Smith, Jul 28 2009
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Amarnath Murthy, May 28 2001
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org) and Jason Earls, May 28 2001.
Better description from Dean Hickerson, Jun 06 2001
Divided g.f. by x to match the offset. - Philippe Deléham, Feb 23 2014
STATUS
approved