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 A033998 #17 Apr 03 2023 10:36:09 %S A033998 23,22073,67187,79427,10729219,3531577135439 %N A033998 Numbers n such that the sum of the primes <= n is a square. %H A033998 G. L. Honaker Jr. and C. Caldwell, <a href="https://t5k.org/curios/page.php?curio_id=179">Prime Curios!: 9</a> %H A033998 G. L. Honaker Jr. and C. Caldwell, <a href="https://t5k.org/curios/page.php?curio_id=12250">Prime Curios!: 3531577135439</a> %H A033998 C. Riveras, PrimePuzzles.Net, <a href="http://www.primepuzzles.net/puzzles/puzz_009.htm">Problem 9: Sum of first k primes is perfect square</a> %F A033998 a(n) = Prime(A033997(n)) %e A033998 2+3+5+7+11+13+17+19+23 = 10^2 is a square, so 23 is in the sequence. %t A033998 Prime[#]&/@Flatten[Position[Accumulate[Prime[Range[710000]]],_?(IntegerQ[ Sqrt[#]]&)]] (* This program will generate the first 5 terms of the sequence. *) (* _Harvey P. Dale_, Jun 22 2013 *) %o A033998 (PARI) s=0;forprime(p=2,1e6,if(issquare(s+=p),print1(p", "))) \\ _Charles R Greathouse IV_, Feb 01 2013 %Y A033998 Cf. A000040, A033997, A061888, A061890. %K A033998 nonn %O A033998 1,1 %A A033998 Calculated by _Jud McCranie_ %E A033998 3531577135439 from _Giovanni Resta_, May 27 2003 %E A033998 Edited by _Ray Chandler_, Mar 20 2007