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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A098353 Multiplication table of the odd numbers read by antidiagonals.

Original entry on oeis.org

1, 3, 3, 5, 9, 5, 7, 15, 15, 7, 9, 21, 25, 21, 9, 11, 27, 35, 35, 27, 11, 13, 33, 45, 49, 45, 33, 13, 15, 39, 55, 63, 63, 55, 39, 15, 17, 45, 65, 77, 81, 77, 65, 45, 17, 19, 51, 75, 91, 99, 99, 91, 75, 51, 19, 21, 57, 85, 105, 117, 121, 117, 105, 85, 57, 21
Offset: 1

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Author

Douglas Stones (dssto1(AT)student.monash.edu.au), Sep 04 2004

Keywords

Comments

a(n) is also the first row of the denominators of the Gram Matrix generated from the normal equations with inner product of the 2D integral with both ranges -1 to 1 over all even 2D polynomials. Subsequent rows and remaining Gram Matrix rows for other 2D polynomials do not currently appear in the OEIS. - John Spitzer, Feb 13 2020

Examples

			Array begins:
   1,  3,  5,  7,  9,  11 ...
   3,  9, 15, 21, 27,  33 ...
   5, 15, 25, 35, 45,  55 ...
   7, 21, 35, 49, 63,  77 ...
   9, 27, 45, 63, 81,  99 ...
  11, 33, 55, 77, 99, 121 ...
		

Crossrefs

Programs

  • GAP
    Flat(List([1..12], n-> List([1..n], k-> Maximum(2*k-1, 2*(n-k)+1) *Minimum(2*k-1, 2*(n-k)+1) ))) # G. C. Greubel, Jul 23 2019
  • Magma
    [[Max(2*k-1, 2*(n-k)+1)*Min(2*k-1, 2*(n-k)+1): k in [1..n]]: n in [1..12]]; // G. C. Greubel, Jul 23 2019
    
  • Maple
    seq(seq(max(2*k-1, 2*(n-k)+1)*min(2*k-1, 2*(n-k)+1), k = 1..n), n = 1..12); # G. C. Greubel, Aug 16 2019
  • Mathematica
    Table[Max[2*k-1, 2*(n-k)+1]*Min[2*k-1, 2*(n-k)+1], {n,0,12}, {k,0,n} ]//Flatten (* G. C. Greubel, Jul 23 2019 *)
  • PARI
    {T(n, k) = max(2*k-1, 2*(n-k)+1)*min(2*k-1, 2*(n-k)+1)};
    for(n=1, 12, for(k=1, n, print1(T(n, k), ", "))) \\ G. C. Greubel, Jul 23 2019
    
  • Sage
    [[max(2*k-1, 2*(n-k)+1)*min(2*k-1, 2*(n-k)+1) for k in (1..n)] for n in (1..12)] # G. C. Greubel, Jul 23 2019
    

Formula

a(n) = A204022(n,k) * A157454(n,k). - Ridouane Oudra, Jul 20 2019
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