A293985 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. exp(x/(1-x))/(1-x)^k.
1, 1, 1, 1, 2, 3, 1, 3, 7, 13, 1, 4, 13, 34, 73, 1, 5, 21, 73, 209, 501, 1, 6, 31, 136, 501, 1546, 4051, 1, 7, 43, 229, 1045, 4051, 13327, 37633, 1, 8, 57, 358, 1961, 9276, 37633, 130922, 394353, 1, 9, 73, 529, 3393, 19081, 93289, 394353, 1441729, 4596553
Offset: 0
Examples
Square array begins: 1, 1, 1, 1, 1, ... A000012; 1, 2, 3, 4, 5, ... A000027; 3, 7, 13, 21, 31, ... A002061; 13, 34, 73, 136, 229, ... A135859; 73, 209, 501, 1045, 1961, ... 501, 1546, 4051, 9276, 19081, ... Antidiagonal rows begin as: 1; 1, 1; 1, 2, 3; 1, 3, 7, 13; 1, 4, 13, 34, 73; 1, 5, 21, 73, 209, 501; - _G. C. Greubel_, Mar 09 2021
Links
- Seiichi Manyama, Antidiagonals n = 0..139, flattened
- Wikipedia, Laguerre polynomials
- Index entries for sequences related to Laguerre polynomials
Crossrefs
Programs
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Magma
function t(n,k) if n eq 0 then return 1; else return Factorial(n-1)*(&+[(j+k)*t(n-j,k)/Factorial(n-j): j in [1..n]]); end if; return t; end function; [t(k,n-k): k in [0..n], n in [0..12]]; // G. C. Greubel, Mar 09 2021
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Mathematica
t[n_, k_]:= t[n, k]= If[n==0, 1, (n-1)!*Sum[(j+k)*t[n-j,k]/(n-j)!, {j,n}]]; T[n_,k_]:= t[k,n-k]; Table[T[n,k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Mar 09 2021 *)
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Sage
@CachedFunction def t(n,k): return 1 if n==0 else factorial(n-1)*sum( (j+k)*t(n-j,k)/factorial(n-j) for j in (1..n) ) def T(n,k): return t(k,n-k) flatten([[T(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Mar 09 2021
Formula
A(0,k) = 1 and A(n,k) = (n-1)! * Sum_{j=1..n} (j+k)*A(n-j,k)/(n-j)! for n > 0.
A(0,k) = 1, A(1,k) = k+1 and A(n,k) = (2*n-1+k)*A(n-1,k) - (n-1)*(n-2+k)*A(n-2,k) for n > 1.
From Seiichi Manyama, Jan 25 2025: (Start)
A(n,k) = n! * Sum_{j=0..n} binomial(n+k-1,j)/(n-j)!.
A(n,k) = n! * LaguerreL(n, k-1, -1). (End)
Comments