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 A157940 #3 Jul 14 2012 11:32:24 %S A157940 8,12,18,24,30,40,45,56,63,70,84,98,105,112,132,154,165,182,195,208, %T A157940 234,260,273,286,306,340,357,380,399,418,456,475,494,513,552,575,598, %U A157940 621,644,690,736,759,782,805,828,870,928,957,992,1023,1054,1085,1116,1178 %N A157940 Numbers n divisible by the largest prime <= sqrt(n) which are not in A001248 (primes squared) or A006094 (product of two consecutive primes). %C A157940 A subsequence of A157941. %F A157940 A157940 = A157942 \ A157936 = A157941 \ A006094, where A157941 = A157942 \ A001248. %e A157940 For numbers less than 4 the definition does not make sense, since there's no prime < 2=sqrt(4). %e A157940 a(1)=8 which is divisible by 2 = precprime(sqrt(8)) and neither a prime squared (as would be 4 and 9) nor product of consecutive primes. %e A157940 5 and 7 are not in this sequence, since not a multiple of 2=precprime(sqrt(5)) =precprime(sqrt(7)). %e A157940 6 is not in the sequence, since it is the product of 2=precprime(sqrt(6)) and the following prime, 3. For the same reason, 15 is excluded. %o A157940 (PARI) for( n=5,1999, n % precprime(sqrtint(n)) & next; n % nextprime(sqrtint(n-1)+1) & print1(n",")) %K A157940 nonn %O A157940 1,1 %A A157940 _M. F. Hasler_, Mar 10 2009