cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A379149 Specialization of the Elementary Symmetric Functions e(n) at x_i -> Euler phi(i).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 5, 2, 1, 6, 13, 12, 4, 1, 10, 37, 64, 52, 16, 1, 12, 57, 138, 180, 120, 32, 1, 18, 129, 480, 1008, 1200, 752, 192, 1, 22, 201, 996, 2928, 5232, 5552, 3200, 768, 1, 28, 333, 2202, 8904, 22800, 36944, 36512, 19968, 4608, 1, 32, 445, 3534, 17712, 58416, 128144, 184288, 166016, 84480, 18432
Offset: 0

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Author

Wouter Meeussen, Dec 16 2024

Keywords

Comments

Triangular table with alternating signed sum equal to 0 for n>0,
1
1,-1
1,-2,1
1,-4,5,-2
1,-6,13,-12,4
..
and with alternating signed weighted sum (first moment) also equal to 0 for n>1,
0
0,-1
0,-2,2
0,-4,10,-6
0,-6,26,-36,16
..
also when shifting the weights to start at 1,
1
1,-2
1,-4,3
1,-8,15,-8
1,-12,39,-48,20

Examples

			Triangle begins:
  1;
  1,  1;
  1,  2,  1;
  1,  4,  5,   2;
  1,  6, 13,  12,   4;
  1, 10, 37,  64,  52,  16;
  1, 12, 57, 138, 180, 120, 32;
  ...
		

Crossrefs

Columns k=0-1 give: A000012, A002088.
Main diagonal gives A001088.
T(n,n-1) gives A067578.
Cf. A000010.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1,
           b(n-1)*(1+x*numtheory[phi](n)))
        end:
    T:= (n, k)-> coeff(b(n), x, k):
    seq(seq(T(n, k), k=0..n), n=0..10);  # Alois P. Heinz, Dec 16 2024
  • Mathematica
    Table[CoefficientList[Expand@Product[z EulerPhi[k]+1,{k,0,n}],z,n+1],{n,0,10}]
  • PARI
    row(n) = Vecrev(prod(k=1, n, 1 + 'x * eulerphi(k))) \\ Andrew Howroyd, Dec 16 2024

Formula

T(n,k) = [x^k] Product_{j=1..n} (1 + x*phi(j)). - Andrew Howroyd, Dec 16 2024
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