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.
%I A351602 #30 Nov 14 2022 01:38:36 %S A351602 1,16,81,272,625,1296,2401,4352,6642,10000,14641,22032,28561,38416, %T A351602 50625,69888,83521,106272,130321,170000,194481,234256,279841,352512, %U A351602 391250,456976,538002,653072,707281,810000,923521,1118208,1185921,1336336,1500625,1806624,1874161,2085136 %N A351602 a(n) = n^4 * Sum_{d^2|n} 1 / d^4. %H A351602 Seiichi Manyama, <a href="/A351602/b351602.txt">Table of n, a(n) for n = 1..10000</a> %F A351602 Multiplicative with a(p^e) = p^4*(p^(4*e) - p^(4*floor((e-1)/2)))/(p^4 - 1). - _Sebastian Karlsson_, Feb 25 2022 %F A351602 Sum_{k=1..n} a(k) ~ c * n^5, where c = zeta(6)/5 = Pi^6/4725 = 0.203468... . - _Amiram Eldar_, Nov 13 2022 %t A351602 f[p_, e_] := p^4*(p^(4*e) - p^(4*Floor[(e - 1)/2]))/(p^4 - 1); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 40] (* _Amiram Eldar_, Nov 13 2022 *) %o A351602 (PARI) a(n) = n^4*sumdiv(n, d, if (issquare(d), 1/d^2)); \\ _Michel Marcus_, Feb 15 2022 %Y A351602 Sequences of the form n^k * Sum_{d^2|n} 1/d^k for k = 0..10: A046951 (k=0), A340774 (k=1), A351600 (k=2), A351601 (k=3), this sequence (k=4), A351603 (k=5), A351604 (k=6), A351605 (k=7), A351606 (k=8), A351607 (k=9), A351608 (k=10). %Y A351602 Cf. A013664. %K A351602 nonn,mult %O A351602 1,2 %A A351602 _Wesley Ivan Hurt_, Feb 14 2022