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 A079143 #5 Oct 01 2013 17:57:33
%S A079143 2,4,6,9,20,25,42,49,110,121,156,169,272,289,342,361,506,529,812,841,
%T A079143 930,961,1332,1369,1640,1681,1806,1849,2162,2209,2756,2809,3422,3481,
%U A079143 3660,3721,4422,4489,4970,5041,5256,5329,6162,6241,6806,6889,7832,7921
%N A079143 Numbers divisible by prime ceilings of their square roots + 1.
%C A079143 n is in the sequence if r=ceiling(sqrt(n)) is prime and r divides n.
%C A079143 Union of the 2 sequences A001248={p^2} and A036689={p(p-1)} for p prime.
%C A079143 Sum of the reciprocals = 1.225...
%F A079143 a(n) = prime(ceiling(n/2))*(prime(ceiling(n/2)) - (n mod 2))
%e A079143 930 is in the sequence because ceiling(sqrt(930)) = 31 and 930/31 = 30.
%t A079143 Flatten[ #(#-{1, 0})&/@Prime/@Range[30]]
%t A079143 a[n_] := (p=Prime[Ceiling[n/2]])(p-Mod[n, 2])
%o A079143 (PARI) ipsqrt(n) = { sr= 0; for(x=1,n, v = ceil(sqrt(x)); if(isprime(v) && x%v == 0, print1(x" "); sr+=1.0/x; ); ); print(); print(sr); } \\ numbers divisible by the prime ceilings of their square roots.
%K A079143 easy,nonn
%O A079143 1,1
%A A079143 _Cino Hilliard_, Dec 26 2002