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 A349539 #35 Dec 03 2021 15:45:06 %S A349539 378,406,528,820,861,1953,2485,3081,5050,5151,5778,7750,9316,11026, %T A349539 11175,18145,19306,19503,36046,36315,39621,92665,93096,130816,131328, %U A349539 135981,205120,326836,337431,661825,816003,1439056,1993006,1995003,2166321,2835771 %N A349539 Smallest number m in a set of at least three consecutive triangular numbers with three distinct prime factors. %e A349539 a(1) = 378 because 378 is the smallest number in the first set of three consecutive triangular numbers with three distinct prime factors, i.e., (378 = 2*3^3*7, 406 = 2*7*29, 435 = 3*5*29). %t A349539 t[n_] := n*(n + 1)/2; q[n_] := PrimeNu[n] == 3; Select[Partition[t /@ Range[3*10^3], 3, 1], AllTrue[#, q] &][[;; , 1]] (* _Amiram Eldar_, Nov 26 2021 *) %Y A349539 Cf. A000217, A128896, A348185. %K A349539 nonn %O A349539 1,1 %A A349539 _Shyam Sunder Gupta_, Nov 25 2021 %E A349539 Name clarified by _Michel Marcus_, Dec 02 2021