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 A376734 #17 Nov 04 2024 02:07:39 %S A376734 332,655,773,943,1007,1018,1033,1046,1117,1172,1277,1333,1358,1369, %T A376734 1424,1622,1667,1783,1810,1828,1865,1907,1928,2008,2216,2252,2293, %U A376734 2348,2404,2447,2473,2518,2567,2608,2645,2698,2711,2726,2797,2898,2942,2972,2978,3031,3048,3049 %N A376734 Numbers k such that 2*k-1 and 2*k+1 are products of exactly three distinct odd primes (A046389). %H A376734 Dominic McCarty, <a href="/A376734/b376734.txt">Table of n, a(n) for n = 1..10000</a> %p A376734 q:= k-> andmap(x-> map(i-> i[2], ifactors(x)[2])=[1$3], [2*k-1, 2*k+1]): %p A376734 select(q, [$1..4000])[]; # _Alois P. Heinz_, Oct 18 2024 %o A376734 (PARI) is_a046389(k) = k%2 && omega(k)==3 && bigomega(k)==3; %o A376734 is_a376734(n) = is_a046389(2*n-1) && is_a046389(2*n+1) %Y A376734 Cf. A046389, A234099, A234102. %K A376734 nonn %O A376734 1,1 %A A376734 _Hugo Pfoertner_, Oct 18 2024