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A123577
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The Kruskal-Macaulay function L_5(n).
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3
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0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 7, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 10, 10, 11, 13, 13, 13, 13, 14, 14, 14, 15, 15, 16, 18, 18, 18, 19, 19, 20, 22, 22, 23, 25, 28, 28, 28, 28, 28, 29, 29, 29, 29, 30, 30, 30, 31, 31, 32, 34, 34, 34, 34, 35, 35, 35, 36, 36
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OFFSET
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0,12
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COMMENTS
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Write n (uniquely) as n = C(n_t,t) + C(n_{t-1},t-1) + ... + C(n_v,v) where n_t > n_{t-1} > ... > n_v >= v >= 1. Then L_t(n) = C(n_t,t+1) + C(n_{t-1},t) + ... + C(n_v,v+1).
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REFERENCES
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D. E. Knuth, The Art of Computer Programming, Vol. 4, Fascicle 3, Section 7.2.1.3, Table 3.
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LINKS
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MAPLE
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lowpol := proc(n, t) local x::integer ; x := floor( (n*factorial(t))^(1/t)) ; while binomial(x, t) <= n do x := x+1 ; od ; RETURN(x-1) ; end: C := proc(n, t) local nresid, tresid, m, a ; nresid := n ; tresid := t ; a := [] ; while nresid > 0 do m := lowpol(nresid, tresid) ; a := [op(a), m] ; nresid := nresid - binomial(m, tresid) ; tresid := tresid-1 ; od ; RETURN(a) ; end: L := proc(n, t) local a ; a := C(n, t) ; add( binomial(op(i, a), t+2-i), i=1..nops(a)) ; end: A123577 := proc(n) L(n, 5) ; end: for n from 0 to 80 do printf("%d, ", A123577(n)) ; od ; # R. J. Mathar, May 18 2007
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MATHEMATICA
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(* The function L(n, t) is defined in A123575 *)
a[n_] := L[n, 5];
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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