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 A281960 #9 Feb 03 2017 12:09:01 %S A281960 61,79,107,139,163,191,211,263,271,373,443,617,719,733,761,971,991, %T A281960 1097,1129,1231,1259,1373,1439,1531,1543,1597,1663,1697,1733,1753, %U A281960 1777,1831,2053,2081,2099,2137,2161,2213,2383,2423,2543,2677,2687,2719,2777,2843,2917 %N A281960 Primes that are the sum of three consecutive odd semiprimes. %H A281960 Charles R Greathouse IV, <a href="/A281960/b281960.txt">Table of n, a(n) for n = 1..10000</a> (1..3263 from K. D. Bajpai) %e A281960 a(1) = 61 is a prime and 61 = 15 + 21 + 25; the sum of three consecutive odd semiprimes. %e A281960 a(2) = 79 is a prime and 79 = 21 + 25 + 33; the sum of three consecutive odd semiprimes. %t A281960 Select[Total /@ Partition[Select[Range[2000], Plus @@ Last /@ FactorInteger[#] == 2 && OddQ[#] &], 3, 1], PrimeQ] %o A281960 (PARI) list(lim)=my(v=List(),u=v,t,L=lim+10); forprime(p=3,L\3, forprime(q=3,min(p,L\p), listput(u,p*q))); u=Set(u); for(i=3,#u, if(isprime(t=u[i-2]+u[i-1]+u[i]), listput(v,t))); while((t=u[#u-1]+u[#u]+L++)<lim, if(bigomega(L)==2, u=concat(u,L); if(t>lim, break); if(isprime(t), listput(v,t)))); Vec(v) \\ _Charles R Greathouse IV_, Feb 03 2017 %Y A281960 Cf. A000040, A001358, A034961, A034962, A281824. %K A281960 nonn %O A281960 1,1 %A A281960 _K. D. Bajpai_, Feb 03 2017