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A306031
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Number of length-n restricted growth strings (RGS) with growth <= seven and first element in [7].
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3
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1, 7, 77, 1071, 17689, 335083, 7117789, 166862583, 4266097185, 117856459427, 3492369757317, 110332338885167, 3697474419284233, 130877053323860507, 4875005854140483629, 190478720135836588519, 7784916624799021983345, 331981949761308979115795
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OFFSET
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0,2
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LINKS
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FORMULA
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E.g.f.: exp(Sum_{j=1..7} (exp(j*x)-1)/j).
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MAPLE
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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);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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