login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A283333 Main diagonal of A283272. 5
1, -1, -4, -19, -55, 5179, 408149, 23366098, -2659962750, -2946880278857, -1715161696081878, 603927037021100215, 9904716216487281046207, 52286804207990141325901614, -71925062774291844591785748425, -17522340813140430159774329947096591 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
FORMULA
a(n) = [x^n] Product_{k=1..n} (1 - x^k)^(k^n). - Ilya Gutkovskiy, Mar 06 2018
PROG
(Ruby)
require 'prime'
def power(a, n)
return 1 if n == 0
k = power(a, n >> 1)
k *= k
return k if n & 1 == 0
return k * a
end
def sigma(x, i)
sum = 1
pq = i.prime_division
if x == 0
pq.each{|a, n| sum *= n + 1}
else
pq.each{|a, n| sum *= (power(a, (n + 1) * x) - 1) / (power(a, x) - 1)}
end
sum
end
def A(k, m, n)
ary = [1]
s_ary = [0] + (1..n).map{|i| sigma(k, i * m)}
(1..n).each{|i| ary << (1..i).inject(0){|s, j| s - ary[-j] * s_ary[j]} / i}
ary
end
def A283333(n)
(0..n).map{|i| A(i + 1, 1, i)[-1]}
end
CROSSREFS
Cf. A283272.
Sequence in context: A174612 A020496 A108484 * A332697 A134507 A098813
KEYWORD
sign
AUTHOR
Seiichi Manyama, Mar 04 2017
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 19 01:22 EDT 2024. Contains 370952 sequences. (Running on oeis4.)