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A026572 a(n)=T(n,n-3), T given by A026568. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=3. 1
1, 2, 8, 19, 56, 140, 376, 953, 2474, 6286, 16097, 40880, 104069, 264052, 670414, 1699831, 4310546, 10924970, 27690075, 70168812, 177820791, 450618964, 1142004584, 2894347667, 7336297080, 18597140982, 47148420564 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

COMMENTS

Also, a(n)=T(n,n-3), T given by A026584. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=3.

Cf. A026568, A026584.

LINKS

Table of n, a(n) for n=3..29.

FORMULA

G.f.: (1/2)*((-3*x^2-x+1)*((x-1)/(4*x^2+x-1))^(1/2)-1+x+x^2)/x^3  - based on guessed recurrence,  Mark van Hoeij, Oct 30 2011.

Conjecture: (n+3)*a(n) +(-3*n-5)*a(n-1) +4*(-n-1)*a(n-2) +(13*n-9)*a(n-3) +(5*n-9)*a(n-4) +6*(-2*n+7)*a(n-5)=0. - R. J. Mathar, Jun 23 2013

CROSSREFS

Sequence in context: A126877 A107769 A026588 * A074797 A240285 A129445

Adjacent sequences:  A026569 A026570 A026571 * A026573 A026574 A026575

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified April 23 13:43 EDT 2014. Contains 240929 sequences.