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 A334782 #10 Sep 08 2022 08:46:25 %S A334782 1,3,7,15,11,21,15,23,16,33,23,45,27,45,77,103,35,48,39,105,105,69,47, %T A334782 77,86,81,124,141,59,231,63,199,161,105,165,108,75,117,189,153,83,315, %U A334782 87,213,176,141,95,397,162,258,245,249,107,372,253,205,273,177 %N A334782 a(n) = Sum_{d|n} lcm(d, tau(d)). %F A334782 a(p) = 2p + 1 for p = odd primes (A065091). %e A334782 a(6) = lcm(1, tau(1)) + lcm(2, tau(2)) + lcm(3, tau(3)) + lcm(6, tau(6)) = lcm(1, 1) + lcm(2, 2) + lcm(3, 2) + lcm(6, 4) = 1 + 2 + 6 + 12 = 21. %t A334782 a[n_] := DivisorSum[n, LCM[#, DivisorSigma[0, #]] &]; Array[a, 100] (* _Amiram Eldar_, May 10 2020 *) %o A334782 (Magma) [&+[LCM(d, #Divisors(d)): d in Divisors(n)]: n in [1..100]] %o A334782 (PARI) a(n) = sumdiv(n, d, lcm(d, numdiv(d))); \\ _Michel Marcus_, May 10 2020 %Y A334782 Cf. A322979 (Sum_{d|n} gcd(d, tau(d))), A334783 (Sum_{d|n} lcm(d, sigma(d))). %Y A334782 Cf. A000005 (tau(n)), A000203 (sigma(n)), A009230 (lcm(n, tau(n))). %K A334782 nonn %O A334782 1,2 %A A334782 _Jaroslav Krizek_, May 10 2020