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 A192231 #26 Aug 18 2025 00:09:30 %S A192231 1,123,124,125,126,306,330,538,539,540,904,905,906,1147,1148,1149, %T A192231 1150,1346,1347,1348,1349,1350,1351,1352,1353,1354,1355,1356,1357, %U A192231 1358,1359,1360,1689,1690,1691,1692,1971,1972,2200,2201 %N A192231 Numbers k without prime numbers in the range (k-3*sqrt(sqrt(k)), k]. %C A192231 a(934) = 20831532 is probably the last term. Any further terms must be greater than 1.5 * 10^18. - _Charles R Greathouse IV_, Jun 27 2011 %H A192231 Charles R Greathouse IV, <a href="/A192231/b192231.txt">Table of n, a(n) for n = 1..934</a> %e A192231 a(2)=123 because (123-3*sqrt(sqrt(123)), 123]=(123-9,9907.., 123]=(113,0092.., 123]. %t A192231 Select[Range[2000], PrimePi[# - 3Sqrt[Sqrt[#]]] == PrimePi[#] &] (* _Alonso del Arte_, Jun 27 2011 *) %o A192231 (PARI) isA192231(n)=nextprime(floor(n+1-3*n^.25))>n \\ _Charles R Greathouse IV_, Jun 27 2011 %o A192231 (PARI) is(n)=for(k=0,sqrtnint(81*n-1,4),if(isprime(n-k), return(0))); 1 \\ _Charles R Greathouse IV_, Aug 26 2015 %Y A192231 Subsequence of A192226. %Y A192231 Cf. A001223, A188817, A189025, A192926. %K A192231 nonn %O A192231 1,2 %A A192231 _Juri-Stepan Gerasimov_, Jun 26 2011 %E A192231 a(2) added by _Alonso del Arte_, Jun 27 2011