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 A104103 #30 Jul 28 2022 15:19:48 %S A104103 2,2,3,3,4,4,5,5,5,6,6,7,7,7,7,8,8,8,9,9,9,9,10,10,10,11,11,11,11,11, %T A104103 12,12,12,12,13,13,13,13,13,14,14,14,14,14,15,15,15,15,16,16,16,16,16, %U A104103 16,17,17,17,17,17,17,17,18,18,18,18,18,19,19,19,19,19,19 %N A104103 a(n) = ceiling(sqrt(prime(n))). %C A104103 Number of squares (including 0) less than prime(n). %H A104103 Charles R Greathouse IV, <a href="/A104103/b104103.txt">Table of n, a(n) for n = 1..10000</a> %F A104103 a(n) = A000196(A000040(n)) + 1. (Although ceiling(sqrt(n)) = A000196(n-1) + 1 in general, the -1 is not needed here since no prime is a square.) - _M. F. Hasler_, Aug 23 2012 %e A104103 a(5)=4 because prime(5)=11 and there are 4 squares <= 11, namely 0, 1, 4 and 9. %t A104103 Ceiling[Sqrt[Prime[Range[80]]]] (* _Harvey P. Dale_, May 09 2020 *) %o A104103 (PARI) A104103(n)=sqrtint(prime(n))+1 /* More than twice as fast as the "trivial" implementation using ceil(sqrt(p)), and avoids errors due to insufficient realprecision (although this is unlikely to be an issue, since prime(n) is limited to precomputed primes < primelimit). */ \\ _Charles R Greathouse IV_ and _M. F. Hasler_, Aug 23 2012 %o A104103 (PARI) apply(n->sqrtint(n)+1,primes(100)) \\ _Charles R Greathouse IV_, Aug 23 2012 %o A104103 (Python) %o A104103 from math import isqrt %o A104103 from sympy import prime %o A104103 def A104103(n): return 1+isqrt(prime(n)) # _Chai Wah Wu_, Jul 28 2022 %K A104103 nonn %O A104103 1,1 %A A104103 _Giovanni Teofilatto_, Mar 04 2005 %E A104103 Edited by _Zak Seidov_, Sep 24 2007 %E A104103 Several terms >= 9 corrected, following an observation by Kevin Ryde, by _M. F. Hasler_, Aug 23 2012