A080849 a(n) = (mu(n)+2)*n^2, where mu is the Moebius function (A008683).

3, 4, 9, 32, 25, 108, 49, 128, 162, 300, 121, 288, 169, 588, 675, 512, 289, 648, 361, 800, 1323, 1452, 529, 1152, 1250, 2028, 1458, 1568, 841, 900, 961, 2048, 3267, 3468, 3675, 2592, 1369, 4332, 4563, 3200, 1681, 1764, 1849, 3872, 4050, 6348, 2209, 4608, 4802

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..5000

Formula

n^2 <= a(n) <= 3*n^2.

a(n) = n * A080848(n) = A000290(n) * A080847(n). - Antti Karttunen, Jul 26 2017

Sum_{n>=1} 1/a(n) = (Pi^4 + 6)/(12*Pi^2). - Amiram Eldar, May 17 2025

Mathematica

Table[(MoebiusMu[n]+2)n^2, {n, 50}] (* Harvey P. Dale, Sep 02 2024 *)

Prog

(Scheme) (define (A080849 n) (* n n (+ 2 (A008683 n)))) ;; Antti Karttunen, Jul 26 2017
(PARI) a(n) = (moebius(n)+2)*n^2; \\ Amiram Eldar, May 17 2025

Crossrefs

Cf. A000290, A008683, A080847, A080848.

Sequence in context: A105229 A237583 A362353 * A058857 A084715 A225467

Adjacent sequences: A080846 A080847 A080848 * A080850 A080851 A080852

Keyword

nonn,easy

Author

Reinhard Zumkeller, Feb 20 2003

Status

approved