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.

A176803 a(n) = the smallest natural numbers m such that product of antiharmonic mean of the divisors of n and antiharmonic mean of the divisors of m are integers, a(n) = 0 if no such number exists.

Original entry on oeis.org

1, 4, 0, 1, 4, 0, 0, 4, 1, 100, 0, 0, 9, 0, 0, 1, 100, 4, 0, 1, 0, 0, 0, 0, 1, 25, 0, 0, 325, 0
Offset: 1

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Author

Jaroslav Krizek, Apr 26 2010

Keywords

Comments

Antiharmonic mean of the divisors of number n is rational number b(n) = A001157(n) / A000203(n) = A158274(n) / A158275(n). a(n) = 1 for infinitely many n. a(n) = 1 for numbers from A020487: a(A020487(n)) = 1. a(n) = 1 iff A158275(n) = 1. a(n) = 0 for infinitely many n. a(n) = 0 for even A158275(n).

Examples

			For n = 10; b(10) = 65/9, a(n) = 100 because b(100) = 63; 65/9 * 63 = 455 (integer).