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A306031 Number of length-n restricted growth strings (RGS) with growth <= seven and first element in [7]. 3
1, 7, 77, 1071, 17689, 335083, 7117789, 166862583, 4266097185, 117856459427, 3492369757317, 110332338885167, 3697474419284233, 130877053323860507, 4875005854140483629, 190478720135836588519, 7784916624799021983345, 331981949761308979115795 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..421

FORMULA

E.g.f.: exp(Sum_{j=1..7} (exp(j*x)-1)/j).

MAPLE

b:= proc(n, m) option remember; `if`(n=0, 1,

      add(b(n-1, max(m, j)), j=1..m+7))

    end:

a:= n-> b(n, 0):

seq(a(n), n=0..25);

# second Maple program:

a:= n-> n!*coeff(series(exp(add((exp(j*x)-1)/j, j=1..7)), x, n+1), x, n):

seq(a(n), n=0..25);

CROSSREFS

Column k=7 of A306024.

Cf. A305967.

Sequence in context: A246236 A267709 A234466 * A249933 A107866 A034176

Adjacent sequences:  A306028 A306029 A306030 * A306032 A306033 A306034

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jun 17 2018

STATUS

approved

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Last modified January 22 22:16 EST 2020. Contains 331166 sequences. (Running on oeis4.)