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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A353386 Sums of two squares obtained by expanding a k X k matrix to (k+1) X (k+1) and taking the not yet seen squared distances of all positions in the matrix.

Original entry on oeis.org

1, 2, 4, 5, 8, 9, 10, 13, 18, 16, 17, 20, 25, 32, 26, 29, 34, 41, 50, 36, 37, 40, 45, 52, 61, 72, 49, 53, 58, 65, 74, 85, 98, 64, 68, 73, 80, 89, 100, 113, 128, 81, 82, 90, 97, 106, 117, 130, 145, 162, 101, 104, 109, 116, 125, 136, 149, 164, 181, 200, 121, 122, 137, 146, 157, 170, 185, 202, 221, 242
Offset: 1

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Author

Hugo Pfoertner, Apr 15 2022

Keywords

Comments

The terms are a permutation of the positive terms of A001481.

Examples

			The sequence can be viewed as a table with line lengths A047800(k+1) - A047800(k), in which the not yet seen sums of squares form a table line. The table starts:
   1,  2,
   4,  5,  8,
   9, 10, 13, 18,
  16, 17, 20, 25, 32,
  26, 29, 34, 41, 50,
  36, 37, 40, 45, 52, 61, 72,
  49, 53, 58, 65, 74, 85, 98
		

Crossrefs

Cf. A353387 (first term in lines), A001105 (last term in lines).

Programs

  • PARI
    a353386(nmax)={my(v=vectorsmall(2*nmax^2)); for(n=1,nmax,
    for(k=0,n,my(s=n^2+k^2); if(!v[s],print1(s,", ");v[s]++));print())};
    a353386(11)
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