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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A303269 Sum of squares of odd digits minus sum of squares of even digits of n.

Original entry on oeis.org

0, 1, -4, 9, -16, 25, -36, 49, -64, 81, 1, 2, -3, 10, -15, 26, -35, 50, -63, 82, -4, -3, -8, 5, -20, 21, -40, 45, -68, 77, 9, 10, 5, 18, -7, 34, -27, 58, -55, 90, -16, -15, -20, -7, -32, 9, -52, 33, -80, 65, 25, 26, 21, 34, 9, 50, -11, 74, -39, 106, -36, -35, -40, -27
Offset: 0

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Author

M. F. Hasler, May 18 2018

Keywords

Comments

Up to 10^4, resp. 10^5, there are 5824, resp. 59316, positive terms. All terms from a(1) to a(11111) are nonzero: see A076164 for indices of zeros.

Crossrefs

Cf. A076164, A071650, A036301.

Programs

  • PARI
    A303269(n)=-vecsum(apply(d->d^2*(-1)^d,digits(n)))
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