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 A219669 #15 Jul 13 2023 01:53:25 %S A219669 2,3,5,7,11,13,17,19,23,29,31,37,41,47,53,59,61,71,73,79,89,97,101, %T A219669 107,109,127,149,151,163,179,181,191,193,199,239,241,251,257,269,271, %U A219669 359,383,401,431,433,449,479,487,499,541,577,599,601,641,647,719,751 %N A219669 Primes neighboring a 5-smooth number. %C A219669 This is to A219528 as 3-smooth numbers A003586 are to 5-smooth numbers A051037. %H A219669 Amiram Eldar, <a href="/A219669/b219669.txt">Table of n, a(n) for n = 1..10000</a> %F A219669 Primes INTERSECTION {2^i 3^j 5^k +/-1 for i,j,k >= 0}. %e A219669 a(1) = 2 = 2^0 * 3^0 * 5^0 + 1 = 2^0 * 3^1 * 5^0 - 1. %t A219669 mx = 2^10; t5 = Select[Sort[Flatten[Table[2^i * 3^j * 5^k, {i, 0, Log[2, mx]}, {j, 0, Log[3, mx]}, {k, 0, Log[5, mx]}]]], # <= mx &]; Union[Select[t5 + 1, PrimeQ], Select[t5 - 1, PrimeQ]] (* _T. D. Noe_, Nov 25 2012 *) %Y A219669 Cf. A000040, A051037, A219528. %K A219669 nonn,easy %O A219669 1,1 %A A219669 _Jonathan Vos Post_, Nov 24 2012 %E A219669 Corrected by _T. D. Noe_, Nov 25 2012