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 A344194 #19 May 11 2021 10:35:08 %S A344194 1,5,10,87,36,4114,134,65629,19705,1048628,2058,2176786622,8204, %T A344194 268435614,1073741928,152587956347,131088,101559956696337,524306, %U A344194 3656158441111964,4398046511420,17592186046514,8388630,4722366482871822135514,847288609591,4503599627378748 %N A344194 a(n) = Sum_{k=1..n} tau(gcd(k,n))^gcd(k,n), where tau(n) is the number of divisors of n. %F A344194 a(n) = Sum_{d|n} phi(n/d) * tau(d)^d. %F A344194 If p is prime, a(p) = 2^p - 1 + p. %t A344194 a[n_] := DivisorSum[n, EulerPhi[n/#] * DivisorSigma[0, #]^# &]; Array[a, 26] (* _Amiram Eldar_, May 11 2021 *) %o A344194 (PARI) a(n) = sum(k=1, n, numdiv(gcd(k, n))^gcd(k, n)); %o A344194 (PARI) a(n) = sumdiv(n, d, eulerphi(n/d)*numdiv(d)^d); %Y A344194 Cf. A000005, A342423, A344081, A344140, A344195. %K A344194 nonn %O A344194 1,2 %A A344194 _Seiichi Manyama_, May 11 2021