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 A001748 #67 Feb 16 2025 08:32:24 %S A001748 6,9,15,21,33,39,51,57,69,87,93,111,123,129,141,159,177,183,201,213, %T A001748 219,237,249,267,291,303,309,321,327,339,381,393,411,417,447,453,471, %U A001748 489,501,519,537,543,573,579,591,597,633,669,681,687,699,717,723,753 %N A001748 a(n) = 3 * prime(n). %C A001748 Semiprimes divisible by 3. - _Jianing Song_, Oct 02 2022 %H A001748 Paolo P. Lava, <a href="/A001748/b001748.txt">Table of n, a(n) for n = 1..20000</a> %H A001748 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Skeleton.html">Skeleton</a> %F A001748 A164023(a(n)) = A164024(a(n)) = A000040(n). - _Reinhard Zumkeller_, Aug 09 2009 %F A001748 a(n) = 3*A000040(n). - _Omar E. Pol_, Jan 31 2012 %F A001748 A253046(a(n)) < a(n). - _Reinhard Zumkeller_, Dec 26 2014 %t A001748 Prime[Range[22]]*3 (* _Vladimir Joseph Stephan Orlovsky_, Apr 29 2008 *) %o A001748 (PARI) 3*primes(22) \\ _Charles R Greathouse IV_, May 19 2011 %o A001748 (Magma) [3*p: p in PrimesUpTo(300)]; // _Vincenzo Librandi_, Mar 26 2014 %o A001748 (Haskell) %o A001748 a001748 = (* 3) . a000040 -- _Reinhard Zumkeller_, Dec 26 2014 %Y A001748 Subsequence of A001358. %Y A001748 Cf. A000040, A100484, A253046, A164023, A164024, A179545, A253046. %K A001748 nonn,easy %O A001748 1,1 %A A001748 _N. J. A. Sloane_