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 A139390 #22 Jul 02 2024 08:19:39 %S A139390 0,5,17,100,791,5830,42468,327198,2575838,20476640,166554645, %T A139390 1353822880,11150031169,92258920888,769310640408,6447635236133, %U A139390 54292816788848,459112338326268,3896226837717653,33172345145637461,283258796052356059,2425130743589880412,20812174068479995267 %N A139390 Sum of primes <= 3^n. %C A139390 For large n, these numbers can be closely approximated by the number of primes < (3^n)^2. For example, the sum of primes < 3^12 = 11150031169. The number of primes < (3^12)^2 = 3^24 = 11152818693. The error here 0.000250. %C A139390 The second term, 5, is the addition of the primes 2 and 3 since we defined the sequence as less than or equal. %H A139390 Amiram Eldar, <a href="/A139390/b139390.txt">Table of n, a(n) for n = 0..43</a> (calculated using Kim Walisch's primesum program) %H A139390 Cino Hilliard, <a href="http://docs.google.com/Doc?id=dgpq9w4b_26dtrq634m">Sum of Primes</a>. [broken link] %H A139390 Cino Hilliard, <a href="http://docs.google.com/Docdocid=dgpq9w4b_11m7tc9r&hl=en">Sumprimesgmp program</a>. [broken link] %H A139390 Kim Walisch, <a href="https://github.com/kimwalisch/primesum">Sum of the primes below x (primesum)</a>. %F A139390 a(n) = A034387(A000244(n)). - _Amiram Eldar_, Jul 02 2024 %o A139390 (PARI) a(n) = vecsum(primes([1, 3^n])); \\ _Michel Marcus_, Jul 02 2024 %Y A139390 Cf. A000244, A034387, A130739. %K A139390 nonn %O A139390 0,2 %A A139390 _Cino Hilliard_, Jun 09 2008 %E A139390 Duplicated term removed and a(20)-a(22) added by _Amiram Eldar_, Jul 02 2024