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 A183140 #14 Apr 10 2018 14:15:27 %S A183140 0,0,0,1,2,3,5,7,9,11,14,17,20,24,28,32,36,41,46,51,57,63,69,76,83,90, %T A183140 97,105,113,121,130,139,148,157,167,177,187,198,209,220,232,244,256, %U A183140 268,281,294,307,321,335,349,363,378,393,408 %N A183140 a(n) = [1/s]+[2/s]+...+[n/s], where s=2+sqrt(2) and []=floor. %C A183140 A183139(n) + a(n) = A000217(n) (the triangular numbers). %H A183140 G. C. Greubel, <a href="/A183140/b183140.txt">Table of n, a(n) for n = 0..10000</a> %F A183140 a(n) = [1/s]+[2/s]+...+[n/s], where s=2+sqrt(2) and []=floor. %t A183140 Accumulate[Floor[Range[60]/(2+Sqrt[2])]] (* _Harvey P. Dale_, Oct 20 2017 *) %o A183140 (PARI) default(realprecision,100); s=2+sqrt(2); for(n=1,99,print1(sum(k=1,n,floor(k/s)),", ")) %Y A183140 Cf. A183139, A000217. %K A183140 nonn %O A183140 0,5 %A A183140 _Clark Kimberling_, Dec 26 2010