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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A224511 Roots of squares generated in A221643. That is, S = i^2 XOR (i+1)^2; increment i; if S is a square then square root of S is appended to a(n). Initially i=0. XOR is the binary logical exclusive-or operator.

Original entry on oeis.org

1, 5, 3, 9, 7, 13, 11, 21, 17, 15, 43, 45, 29, 19, 41, 25, 23, 59, 39, 27, 35, 33, 31, 85, 37, 61, 51, 53, 47, 81, 79, 49, 55, 121, 83, 75, 57, 73, 77, 67, 65, 63, 71, 69, 125, 89, 87, 123, 105, 107, 95, 101, 163, 93, 91, 99, 97, 349, 243, 103, 169, 109, 233, 115, 119, 171
Offset: 1

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Author

Alex Ratushnyak, Apr 08 2013

Keywords

Comments

Conjecture: this is a permutation of odd numbers.
b(n) = (a(n)-1)/2 begins: 0, 2, 1, 4, 3, 6, 5, 10, 8, 7, 21, 22, 14, 9, 20, 12, 11, 29, 19, 13, 17.

Crossrefs

Programs

  • Python
    import math
    for i in range(1<<16):
        s = (i*i) ^ ((i+1)*(i+1))
        r = int(math.sqrt(s));
        if s == r*r:
            print(r, end=', ')
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