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1, 1, 1, 1, 3, 1, 1, 4, 4, 1, 1, 6, 8, 6, 1, 1, 6, 12, 12, 6, 1, 1, 12, 24, 36, 24, 12, 1, 1, 8, 32, 48, 48, 32, 8, 1, 1, 12, 32, 96, 96, 96, 32, 12, 1, 1, 12, 48, 96, 192, 192, 96, 48, 12, 1, 1, 18, 72, 216, 288, 576, 288, 216, 72, 18, 1, 1, 12, 72, 216, 432, 576, 576, 432, 216, 72, 12, 1
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table;
graph;
refs;
listen;
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internal format)
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OFFSET
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0,5
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COMMENTS
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We assume that A175836(0)=1 since it would be the empty product.
These are the generalized binomial coefficients associated with the Dedekind psi function A001615.
Another name might be the psi-nomial coefficients.
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LINKS
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FORMULA
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EXAMPLE
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The first five terms in the Dedekind psi function are 1,3,4,6,6 and so T(4,2) = 6*4*3*1/((3*1)*(3*1))=8 and T(5,3) = 6*6*4*3*1/((4*3*1)*(3*1))=12.
The triangle begins
1
1 1
1 3 1
1 4 4 1
1 6 8 6 1
1 6 12 12 6 1
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MAPLE
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A175836 := proc(n) option remember; local p;
`if`(n<2, 1, n*mul(1+1/p, p=factorset(n))*A175836(n-1)) end:
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MATHEMATICA
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DedekindPsi[n_] := Sum[MoebiusMu[n/d] d^2 , {d, Divisors[n]}]/EulerPhi[n];
(* b = A175836 *) b[n_] := Times @@ DedekindPsi /@ Range[n];
T[n_, k_] := b[n]/(b[k] b[n-k]);
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PROG
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(Sage)
q=100 #change q for more rows
P=[0]+[i*prod([(1+1/x) for x in prime_divisors(i)]) for i in [1..q]]
[[prod(P[1:n+1])/(prod(P[1:k+1])*prod(P[1:(n-k)+1])) for k in [0..n]] for n in [0..len(P)-1]] #generates the triangle up to q rows.
(Haskell)
a238498 n k = a238498_tabl !! n !! k
a238498_row n = a238498_tabl !! n
a238498_tabl = [1] : f [1] a001615_list where
f xs (z:zs) = (map (div y) $ zipWith (*) ys $ reverse ys) : f ys zs
where ys = y : xs; y = head xs * z
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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