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.

Showing 1-1 of 1 results.

A362935 a(n) = (A000982(n) - A132188(n))/2.

Original entry on oeis.org

0, 0, 1, 1, 3, 5, 8, 10, 12, 16, 21, 25, 31, 37, 44, 48, 56, 62, 71, 79, 89, 99, 110, 120, 128, 140, 151, 163, 177, 191, 206, 218, 234, 250, 267, 279, 297, 315, 334, 352, 372, 392, 413, 433, 453, 475, 498, 518, 536, 556, 581, 605, 631, 655, 682, 708, 736, 764, 793, 821, 851, 881, 910, 934, 966, 998
Offset: 1

Views

Author

N. J. A. Sloane, Aug 28 2023

Keywords

Comments

a(n) = one-half of (number of pairs (i,j) in [1..n] X [1..n] with integral arithmetic mean) - (number of pairs (i,j) in [1..n] X [1..n] with integral geometric mean).

Crossrefs

Programs

  • Python
    from sympy.ntheory.primetest import is_square
    def A362935(n): return ((n-1)**2>>2)-sum(1 for x in range(1,n+1) for y in range(1,x) if is_square(x*y)) # Chai Wah Wu, Aug 29 2023

Formula

a(n) = A362934(n)/2.
Showing 1-1 of 1 results.