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 A131260 #8 Jul 11 2015 16:46:19
%S A131260 4,5,6,7,11,22,66,88,202,212,242,272,404,444,464,474,595,656,707,757,
%T A131260 777,808,828,838,868,888,969,989,1111,1881,2222,2772,3553,4444,5005,
%U A131260 5335,5555,5665,5995,6006,6556,6886,8448,8668,8888,9229,9339,10601
%N A131260 a(n) is the least palindrome > a(n-1) such that a(1) + a(2) + ... + a(n) is a semiprime.
%C A131260 Semiprime analog of A051934. The semiprime partial sums begin 4, 9, 15, 22, 33, 55, 121, 209, 411, 623, 865, 1137, 1541, 1985, 2449, 2923, - _R. J. Mathar_, Nov 09 2007
%e A131260 a(3) = 6 because that is the smallest palindrome p such that 4+5+p is a semiprime, namely 4+5+6 = 15 = 3*5.
%p A131260 isA001358 := proc(n) if numtheory[bigomega](n) = 2 then true ; else false; fi ; end: isA002113 := proc(n) local i,digs ; if n < 10 then true; else digs := convert(n,base,10) ; for i from 1 to nops(digs) do if op(i,digs) <> op(-i,digs) then RETURN(false) ; fi ; od: RETURN(true) ; fi ; end: A131260 := proc(n) option remember ; local a,i ; if n = 1 then 4; else for a from A131260(n-1)+1 do if isA002113(a) and isA001358( a+add(A131260(i),i=1..n-1) ) then RETURN(a) ; fi ; od: fi ; end: seq(A131260(n),n=1..70) ; # _R. J. Mathar_, Nov 09 2007
%t A131260 a = {4, 5}; Do[i = a[[ -1]] + 1; While[Not[FromDigits[Reverse[IntegerDigits[i]]] == i] || Not[Sum[FactorInteger[Plus @@ a + i][[j, 2]], {j, 1, Length[FactorInteger[ Plus @@ a + i]]}] == 2], i++ ]; AppendTo[a, i], {50}]; a (* _Stefan Steinerberger_, Nov 17 2007 *)
%Y A131260 Cf. A001358, A051934.
%K A131260 base,easy,nonn
%O A131260 1,1
%A A131260 _Jonathan Vos Post_, Oct 20 2007
%E A131260 Corrected and extended by _R. J. Mathar_ and _Stefan Steinerberger_, Nov 09 2007