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 A236856 #11 Sep 19 2022 06:24:21
%S A236856 0,1,3,9,21,81,141,561,1401,3921,6441,34161,61881,422241,782601,
%T A236856 1142961,1863681,14115921,26368161,259160721,491953281,724745841,
%U A236856 957538401,6311767281,11665996161,38437140561,65208284961,145521718161,225835151361,2554924714161
%N A236856 Partial sums of A003418 starting summing from A003418(1), with a(0) = 0.
%C A236856 Similar comments about the trailing digits apply here as in A173185.
%C A236856 a(n) gives the position of the last element of row n in irregular tables like A238280.
%C A236856 From a(2)=3 onward all terms are divisible by three.
%C A236856 a(n) is divisible by 73 for n >= 72. Therefore a(n)/3 is prime for only 13 values of n: 3, 4, 6, 8, 9, 12, 16, 22, 23, 31, 35, 48 and 53. - _Amiram Eldar_, Sep 19 2022
%H A236856 Antti Karttunen, <a href="/A236856/b236856.txt">Table of n, a(n) for n = 0..250</a>
%F A236856 a(n) = A173185(n)-1.
%t A236856 Prepend[Accumulate @ Table[LCM @@ Range[n], {n, 1, 30}], 0] (* _Amiram Eldar_, Sep 19 2022 *)
%o A236856 (Scheme) (define (A236856 n) (if (< n 2) n (+ (A236856 (- n 1)) (A003418 n))))
%Y A236856 One less than A173185.
%Y A236856 Cf. A003418, A007489, A231722, A236857, A236858.
%K A236856 nonn
%O A236856 0,3
%A A236856 _Antti Karttunen_, Feb 27 2014