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A027915 a(n) = Sum_{0<=j<=i, 0<=i<=n} A027907(i, j). 2
1, 3, 9, 26, 76, 223, 658, 1948, 5782, 17193, 51194, 152594, 455209, 1358841, 4058439, 12126696, 36248370, 108385917, 324172566, 969801726, 2901883611, 8684735577, 25995833145, 77824036620, 233012973051, 697745695923 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

FORMULA

G.f.: (1+x+1/G(0))/(2*(1-2*x-3*x^2))/(1-x), where G(k)= 1 + x*(2+3*x)*(4*k+1)/(4*k+2 - x*(2+3*x)*(4*k+2)*(4*k+3)/(x*(2+3*x)*(4*k+3) + 4*(k+1)/G(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Jul 30 2013

CROSSREFS

Partial sums of A027914.

Sequence in context: A273343 A101169 A119826 * A295115 A114982 A133405

Adjacent sequences:  A027912 A027913 A027914 * A027916 A027917 A027918

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified January 26 23:05 EST 2020. Contains 331289 sequences. (Running on oeis4.)