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A026570 a(n)=T(n,n-1), T given by A026568. Also a(n) = number of integer strings s(0),...,s(n) counted by T such that s(n)=1. 0
1, 1, 4, 7, 20, 43, 111, 259, 648, 1565, 3885, 9533, 23662, 58547, 145630, 362151, 903110, 2253615, 5633359, 14094035, 35304658, 88511733, 222115782, 557819793, 1401987930, 3526066273, 8874034647, 22346581133, 56304982154 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Also a(n)=T'(n,n-1), T' given by A026584. Also a(n) = number of integer strings s(0),...,s(n) counted by T' such that s(n)=1.

LINKS

Table of n, a(n) for n=1..29.

FORMULA

Conjecture: (n+1)*a(n) -2*n*a(n-1) +(-3*n-1)*a(n-2) +2*(2*n-3)*a(n-3)=0. - R. J. Mathar, Jun 23 2013

CROSSREFS

Sequence in context: A296624 A296663 A066345 * A111955 A244791 A220004

Adjacent sequences:  A026567 A026568 A026569 * A026571 A026572 A026573

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified August 5 13:21 EDT 2021. Contains 346469 sequences. (Running on oeis4.)