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 A288656 #20 Dec 12 2023 13:43:10
%S A288656 0,0,0,2,7,12,22,30,45,57,69,81,104,122,153,184,215,239,280,321,381,
%T A288656 441,501,561,644,716,788,860,932,991,1079,1167,1286,1405,1524,1643,
%U A288656 1762,1864,2003,2142,2281,2401,2562,2723,2927,3131,3335,3539,3790,4018,4246,4474,4702,4930,5211,5492,5773,6054,6335,6616,6956,7267,7639
%N A288656 a(n) = Sum_{k=1..n} Sum_{i=floor((k-1)/2)..k-1} i * c(i), where c is the prime characteristic (A010051).
%C A288656 Sum of all the primes appearing in columns less than or equal to n from the example in A258087.
%p A288656 with(numtheory): A288656:=n->add(add(i*(pi(i)-pi(i-1)), i=floor((k-1)/2)..k-1), k=1..n): seq(A288656(n), n=0..100);
%t A288656 Table[Sum[Sum[i (PrimePi[i] - PrimePi[i - 1]), {i, Floor[(k - 1)/2], k - 1}], {k, n}], {n, 0, 62}] (* _Michael De Vlieger_, Jun 15 2017 *)
%Y A288656 Cf. A010051, A258087.
%Y A288656 Partial Sums of A288726.
%K A288656 nonn,easy
%O A288656 0,4
%A A288656 _Wesley Ivan Hurt_, Jun 12 2017