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 A378314 #14 Nov 23 2024 09:37:31
%S A378314 0,1,2,4,6,12,16,28,36,52,70,118,150,246,318,382,430,670,798,1278,
%T A378314 1566,1886,2270,3230,3742,4702,5854,6814,7966,11806,14878,22558,25630,
%U A378314 32542,40222,46366,52510,70942,86302,100126,112414,149278,172318,246046,295198,344350,405790,553246,626974,774430,897310
%N A378314 a(n) = number of subsets of {1, 2, ..., n} that represent the first k divisors of m for some positive integers m and 1 <= k <= A000005(m).
%F A378314 a(n) = Sum_{i=1..n} sigma(LCM(1,2,...,i)/i).
%e A378314 a(4) = 6 enumerates subsets {1}, {1,2}, {1,2,3}, {1,2,4}, {1,2,3,4}, {1,3}.
%o A378314 (PARI) a378314(n) = my(L=1); sum(i=1,n, L=lcm(L,i); sigma(L/i));
%Y A378314 Partial sums of A190940.
%Y A378314 Cf. A001248, A027750, A064510, A180851, A194269, A307137, A378313.
%K A378314 nonn
%O A378314 0,3
%A A378314 _Max Alekseyev_, Nov 22 2024