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A014369
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a(n) = bcd, where n = C(b,3)+C(c,2)+C(d,1), b>c>d>=0.
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2
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310, 320, 321, 410, 420, 421, 430, 431, 432, 510, 520, 521, 530, 531, 532, 540, 541, 542, 543, 610, 620, 621, 630, 631, 632, 640, 641, 642, 643, 650, 651, 652, 653, 654, 710, 720, 721, 730, 731, 732, 740, 741, 742, 743, 750, 751, 752, 753
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OFFSET
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1,1
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COMMENTS
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In the definition bcd means concatenation not multiplication. - Sean A. Irvine, Oct 18 2018
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REFERENCES
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W. Bruns and J. Herzog, Cohen-Macaulay Rings, Cambridge, 1993, p. 158.
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LINKS
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MAPLE
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invA000292 := proc(n)
local i;
for i from 1 do
if binomial(i+1, 3) > n then
return i;
end if;
end do:
end proc:
invA000217 := proc(n)
local i;
for i from 1 do
if binomial(i+1, 2) > n then
return i;
end if;
end do:
end proc:
local b, c, d ;
b := invA000292(n) ;
c := invA000217(n-binomial(b, 3)) ;
d := n-binomial(b, 3)-binomial(c, 2) ;
digcatL([b, c, d]) ; # of program transforms
end proc:
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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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a(1), a(4), a(10), a(20), a(35) modified to meet constraint b>c>d and more terms from Sean A. Irvine, Oct 18 2018
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STATUS
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approved
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