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 A358864 #12 Feb 16 2025 08:34:04
%S A358864 84,1785,299880,1020510,8897460,102612510,33367223274,249417828660,
%T A358864 9177835927260,10064864238489060,5558913993302670,
%U A358864 15633689593760207970,3792821921183752657200
%N A358864 a(n) is the smallest n-gonal pyramidal number with exactly n distinct prime factors.
%C A358864 The corresponding indices of n-gonal pyramidal numbers are 7, 17, 84, 115, 220, 468, 3058, 5719, 18290, ...
%H A358864 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DistinctPrimeFactors.html">Distinct Prime Factors</a>
%H A358864 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PyramidalNumber.html">Pyramidal Number</a>
%e A358864 a(3) = 84, because 84 is a tetrahedral (or triangular pyramidal) number with 3 distinct prime factors {2, 3, 7} and this is the smallest such number.
%o A358864 (PARI) a(n) = if(n<3, return()); for(k=1, oo, my(t=(k*(k+1)*((n-2)*k + (5-n)))\6); if(omega(t) == n, return(t))); \\ _Daniel Suteu_, Dec 05 2022
%Y A358864 Cf. A001221, A156329, A358862, A358863, A358865.
%K A358864 nonn,more
%O A358864 3,1
%A A358864 _Ilya Gutkovskiy_, Dec 03 2022
%E A358864 a(12)-a(15) from _Daniel Suteu_, Dec 05 2022