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 A161569 #18 May 26 2025 05:15:31 %S A161569 0,2,5,9,13,17,22,28,34,40,47,55,63,71,80,89,98,107,116,126,137,148, %T A161569 159,170,181,193,205,217,230,244,258,272,287,302,317,332,347,363,379, %U A161569 395,411,427,444,462,480,498,516,534,553,572,591,611,632,653,674,695,716 %N A161569 Sum of first n nonprimes minus their indices. %C A161569 The sum of first n nonprimes is in A051349. %C A161569 Partial sums of A073425. - _Jaroslav Krizek_, Jun 27 2009 %F A161569 a(n) = A051349(n)-n*(n+1)/2. %F A161569 a(n) = a(n-1)+A018252(n)-n, a(1) = 0. - _Klaus Brockhaus_, Dec 16 2010 %e A161569 a(1) = 1-1 = 0; a(2) = 0+4-2 = 2, a(3) = 2+6-3 = 5; a(4) = 5+8-4 = 9. %Y A161569 Cf. A073425, A051349, A018252, A112997. %K A161569 nonn,easy %O A161569 1,2 %A A161569 _Juri-Stepan Gerasimov_, Jun 14 2009 %E A161569 a(54)-a(57) from _Stefano Spezia_, May 26 2025