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 A185008 #21 Jul 05 2025 11:24:18 %S A185008 4,14,21,33,46,51,62,74,82,91,106,111,121,133,141,155,161,177,183,194, %T A185008 201,213,221,235,247,253,262,274,287,291,301,314,321,334,341,355,361, %U A185008 371,381,391,403,411,422,437,445,451,466,471,481,493,501,511,526,533 %N A185008 Next semiprime after 10*n. %C A185008 This is to semiprimes A001358 as A218255 is to primes A000040. %H A185008 Harvey P. Dale, <a href="/A185008/b185008.txt">Table of n, a(n) for n = 0..1000</a> %F A185008 a(n) = MIN[k in A218255 and k > 10*n]. %e A185008 a(0) = 4 because 4=2^2 is the least semiprime > 10*0=0. %e A185008 a(1) = 14 because 14=2*7 is the least semiprime > 10*1=10. %t A185008 SemiprimeQ[n_Integer] := If[Abs[n] < 2, False, (2 == Plus @@ Transpose[FactorInteger[Abs[n]]][[2]])]; NextSemiprime[n_] := Module[{m = n + 1}, While[! SemiPrimeQ[m], m++]; m]; Table[NextSemiprime[10*n], {n, 0, 100}] (* _T. D. Noe_, Nov 02 2012 *) %t A185008 nsp[n_]:=Module[{k=n+1},While[PrimeOmega[k]!=2,k++];k]; Table[nsp[10n],{n,0,60}] (* _Harvey P. Dale_, Mar 17 2023 *) %o A185008 (Python) %o A185008 from sympy import primeomega %o A185008 def nextsemiprime(n): %o A185008 while primeomega(n + 1) != 2: n += 1 %o A185008 return n + 1 %o A185008 def a(n): return nextsemiprime(10*n) %o A185008 print([a(n) for n in range(54)]) # _Michael S. Branicky_, Apr 14 2021 %Y A185008 Cf. A001358, A218255. %K A185008 nonn,easy %O A185008 0,1 %A A185008 _Jonathan Vos Post_, Nov 01 2012