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 A105340 #21 Apr 30 2025 15:33:39 %S A105340 0,1,3,6,10,15,21,28,36,45,55,66,78,91,105,120,136,153,171,190,210, %T A105340 231,253,276,300,325,351,378,406,435,465,496,528,561,595,630,666,703, %U A105340 741,780,820,861,903,946,990,1035,1081,1128,1176,1225,1275,1326,1378,1431,1485,1540,1596,1653,1711,1770,1830,1891,1953,2016,32 %N A105340 a(n) = n*(n+1)/2 mod 2048. %C A105340 Period 4096. - _Charles R Greathouse IV_, Oct 16 2012 %H A105340 <a href="/index/Rec#order_4095">Index entries for linear recurrences with constant coefficients</a>, order 4095. %t A105340 Mod[Accumulate[Range[0,70]],2048] (* _Harvey P. Dale_, Sep 18 2019 *) %o A105340 (PARI) a(n)=n*(n+1)/2%2048 \\ _Charles R Greathouse IV_, Oct 16 2012 %o A105340 (Python) %o A105340 def A105340(n): return (n*(n+1)>>1)&2047 # _Chai Wah Wu_, Apr 17 2025 %Y A105340 See A105198 for further information. %Y A105340 Cf. A000217. %K A105340 nonn,easy %O A105340 0,3 %A A105340 _Oscar Takeshita_, May 01 2005 %E A105340 Removed formulas that were wrong at indices >= 65 because the "mod 2048" part of the definition had been ignored _R. J. Mathar_, Jan 26 2010