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 A102515 #35 Jan 01 2021 12:02:22
%S A102515 2,2,3,3,4,4,4,4,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,8,8,8,8,8,8,8,8,9,9,
%T A102515 9,9,9,9,9,9,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11,11,11,
%U A102515 11,12,12,12,12,12,12,12,12,12,12,12,12,13,13,13,13,13,13,13,13,13,13,13
%N A102515 a(n) = floor(1 + sqrt(2n + 1)).
%C A102515 The first occurrence of k appears at floor((k-1)^2/2), beginning with k=3. - _Robert G. Wilson v_, Mar 01 2015
%C A102515 If the sign inside the sqrt() is changed from "+" to "-", then the offset must be changed from 0 to 1 in order for the terms in the data to remain the same. - _Robert G. Wilson v_, Mar 01 2015
%F A102515 With offset 1, a(n) = A339399(n) + A339443(n). - _Wesley Ivan Hurt_, Dec 31 2020
%t A102515 Table[Floor[1+Sqrt[2n+1]],{n,0,100}] (* _Harvey P. Dale_, Feb 28 2015 *)
%K A102515 easy,nonn
%O A102515 0,1
%A A102515 _Giovanni Teofilatto_, Mar 16 2005
%E A102515 Definition corrected by _Olivier Gérard_ & _Harvey P. Dale_, Feb 28 2015
%E A102515 Offset corrected by _Robert G. Wilson v_, Mar 01 2015