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 A295576 #21 Dec 10 2017 19:11:34 %S A295576 0,1,1,1,17,1,98,82,273,82,979,626,2275,707,2674,3108,8772,3027,15333, %T A295576 9044,14994,9669,39974,17668,50085,24310,60597,50470,127687,45604, %U A295576 178312,103496,149908,103496,225302,129750,432345,187017,349830,266088,722666 %N A295576 a(n) = Sum_{1 <= j <= n/2, gcd(j,n)=1} j^4. %C A295576 If p is an odd prime, a(p) = p*(p^2-1)*(3*p^2-7)/480. - _Robert Israel_, Dec 10 2017 %H A295576 Seiichi Manyama, <a href="/A295576/b295576.txt">Table of n, a(n) for n = 1..10000</a> %H A295576 John D. Baum, <a href="http://www.jstor.org/stable/2690056">A Number-Theoretic Sum</a>, Mathematics Magazine 55.2 (1982): 111-113. %p A295576 f:= n -> add(t^4, t = select(t->igcd(t,n)=1, [$1..n/2])): %p A295576 map(f, [$1..100]); # _Robert Israel_, Dec 10 2017 %t A295576 f[n_] := Plus @@ (Select[Range[n/2], GCD[#, n] == 1 &]^4); Array[f, 41] (* _Robert G. Wilson v_, Dec 10 2017 *) %o A295576 (PARI) a(n) = sum(j=1, n\2, (gcd(j, n)==1)*j^4); \\ _Michel Marcus_, Dec 10 2017 %Y A295576 In the Baum (1982) paper, S_1, S_2, S_3, S_4 are A023896, A053818, A053819, A053820, and S'_1, S'_2, S'_3, S'_4 are A066840, A295574, A295575, A295576. %K A295576 nonn %O A295576 1,5 %A A295576 _N. J. A. Sloane_, Dec 08 2017