A179872 Numbers h such that antiharmonic mean B(h) of the numbers k < h such that gcd(k, h) = 1 is not integer.

3, 4, 6, 7, 8, 9, 12, 13, 14, 15, 16, 18, 19, 20, 21, 24, 25, 26, 27, 28, 30, 31, 32, 33, 35, 36, 37, 38, 39, 40, 42, 43, 44, 45, 48, 49, 50, 51, 52, 54, 56, 57, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 84, 86, 87, 88

Offset

1,1

Comments

Numbers h such that B(h) = A053818(h) / A023896(h) = A175505(h) / A175506(h) is not integer.

Numbers h such that A175506(h) > 1.

Complement of A179871.

Union of A007645 and A179891.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

a(6) = 9 because B(9) = A053818(9) / A023896(9) = 159/27 = 53/9 (not integer).

Prog

(PARI) isok(k) = {my(f = factor(k)); if(k == 1, 0, denominator(2*k/3 + (1/3) * prod(i = 1, #f~, 1 - f[i, 1])/eulerphi(f)) > 1); } \\ Amiram Eldar, May 25 2025

Crossrefs

Cf. A179871, A179873, A179874, A179875, A179876, A179877, A179878, A179879, A179880, A179882, A179883, A179884, A179885, A179886, A179887, A179890, A179891.

Sequence in context: A187953 A188024 A362287 * A298644 A075747 A143344

Adjacent sequences: A179869 A179870 A179871 * A179873 A179874 A179875

Keyword

nonn

Author

Jaroslav Krizek, Jul 30 2010, Jul 31 2010

Extensions

More terms from Amiram Eldar, May 25 2025

Status

approved