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 A274120 #32 Feb 09 2025 18:09:19
%S A274120 961,1369,1849,4225,263169,130919364,758451600,29682949232484409
%N A274120 Squares that are the sum of the first k odd primes for some k.
%C A274120 Intersection of A000290 and A071148. [_Felix Fröhlich_, Jun 10 2016]
%C A274120 a(9), if it exists, is larger than 2*10^26 and would require adding more than 3.6*10^12 primes. - _Giovanni Resta_, Jun 12 2016
%H A274120 G. L. Honaker Jr. and C. Caldwell, <a href="https://t5k.org/curios/page.php?number_id=4306">Prime Curios! : 961</a>
%e A274120 961 is in the sequence because 961 = 31^2. Also, 3+5+7+...+83+89 = 961.
%t A274120 Select[s=0;Table[s=s+Prime[k],{k,2,15000000}],IntegerQ[Sqrt[#]]&]
%t A274120 Select[Accumulate[Prime[Range[2,100000]]],IntegerQ[Sqrt[# ]]&] (* _Harvey P. Dale_, May 26 2023 *)
%o A274120 (PARI) my(s = 0); forprime(p=3, 1e10, s += p; if (issquare(s), print1(s, ", ")))
%Y A274120 Cf. A007504, A033997, A061890, A065091, A071148.
%K A274120 nonn,more
%O A274120 1,1
%A A274120 _K. D. Bajpai_, Jun 10 2016
%E A274120 Second comment rephrased by _Harvey P. Dale_, May 26 2023