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 A112456 #12 Aug 05 2021 16:13:46
%S A112456 6,3,10,21,55,78,136,171,253,406,465,666,820,903,1081,1378,1711,1830,
%T A112456 2211,2485,2628,3081,3403,3916,4656,5050,5253,5671,5886,6328,8001,
%U A112456 8515,9316,9591,11026,11325,12246,13203,13861,14878,15931,16290,18145,18528,19306
%N A112456 Least triangular number divisible by n-th prime.
%C A112456 Essentially the same as A008837; only the first terms differ.
%F A112456 a(n) = p*(p-1)/2, for p = prime(n) and n >= 2. - _Michael S. Branicky_, Jun 03 2021
%t A112456 With[{tr=Accumulate[Range[300]]},Table[SelectFirst[tr,Divisible[#,Prime[n]]&],{n,50}]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 06 2018 *)
%o A112456 (PARI)
%o A112456 T(n) = n*(n+1)/2
%o A112456 for(n=1,100, p=prime(n); tr=1; while(T(tr)%p<>0, tr++); print1(T(tr),","))
%o A112456 (Python)
%o A112456 from sympy import prime
%o A112456 def a(n):
%o A112456 if n == 1: return 6
%o A112456 p = prime(n)
%o A112456 return p*(p-1)//2
%o A112456 print([a(n) for n in range(1, 46)]) # _Michael S. Branicky_, Jun 03 2021
%Y A112456 Cf. A000217 (triangular numbers), A008837 (p(p-1)/2 for p prime).
%K A112456 nonn
%O A112456 1,1
%A A112456 _Rick L. Shepherd_, Sep 06 2005