A257644 First differences of A264100.

1, 3, 8, 14, 24, 32, 48, 58, 77, 93, 115, 129, 163, 179, 207, 235, 271, 291, 336, 358, 406, 442, 482, 508, 576, 610, 656, 700, 762, 794, 874, 908, 977, 1029, 1087, 1139, 1239, 1279, 1343, 1403, 1501, 1545, 1649, 1695, 1785, 1869, 1945, 1995, 2129, 2189

Offset

0,2

Comments

Cumulative sum of A007503, starting with 1.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Prog

(PARI) alist(n)=my(x); vector(n, k, if(k==1, x=1, x+=sigma(k-1)+numdiv(k-1)))
(Haskell)
a257644 n = a257644_list !! n
a257644_list = scanl (+) 1 a007503_list -- Reinhard Zumkeller, Nov 09 2015
(Python)
from math import isqrt
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

Crossrefs

Cf. A000005, A000203, A007503, A264100.

Sequence in context: A264689 A146158 A062354 * A135940 A126430 A082474

Adjacent sequences: A257641 A257642 A257643 * A257645 A257646 A257647

Keyword

nonn

Author

Franklin T. Adams-Watters, Nov 05 2015

Status

approved