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%I #14 Oct 31 2023 17:52:40
%S 1,3,8,14,24,32,48,58,77,93,115,129,163,179,207,235,271,291,336,358,
%T 406,442,482,508,576,610,656,700,762,794,874,908,977,1029,1087,1139,
%U 1239,1279,1343,1403,1501,1545,1649,1695,1785,1869,1945,1995,2129,2189
%N First differences of A264100.
%C Cumulative sum of A007503, starting with 1.
%H Reinhard Zumkeller, <a href="/A257644/b257644.txt">Table of n, a(n) for n = 0..10000</a>
%o (PARI) alist(n)=my(x);vector(n,k,if(k==1,x=1,x+=sigma(k-1)+numdiv(k-1)))
%o (Haskell)
%o a257644 n = a257644_list !! n
%o a257644_list = scanl (+) 1 a007503_list -- _Reinhard Zumkeller_, Nov 09 2015
%o (Python)
%o from math import isqrt
%o def A257644(n): return (-(s:=isqrt(n))*(s*(s+4)+5)+sum(((q:=n//w)+1)*(q+(w<<1)+4) for w in range(1,s+1))>>1)+1 # _Chai Wah Wu_, Oct 31 2023
%Y Cf. A000005, A000203, A007503, A264100.
%K nonn
%O 0,2
%A _Franklin T. Adams-Watters_, Nov 05 2015
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