A281268 Main diagonal of A284993.

1, -1, -3, -20, -54, 4935, 403432, 23308238, -2635805834, -2939783620152, -1713742918458426, 602896713529233651, 9901041507182530035347, 52279007840299710266340246, -71905380320280305597098525356, -17521448585729172053338909789657052

Offset: 0

Author

Seiichi Manyama, Apr 13 2017

Keywords

• sign

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..80

Crossrefs

Cf. A284993.

Programs

Ruby

def s(k, n)
  s = 0
  (1..n).each{|i| s += (-1) ** (n / i + 1) * i ** k if n % i == 0}
  s
end
def A(k, n)
  ary = [1]
  a = [0] + (1..n).map{|i| s(k + 1, i)}
  (1..n).each{|i| ary << (1..i).inject(0){|s, j| s - a[j] * ary[-j]} / i}
  ary
end
def A281268(n)
  (0..n).map{|i| A(i, i)[-1]}
end

Formula

a(n) = [x^n] Product_{k=1..n} 1/(1 + x^k)^(k^n). - Ilya Gutkovskiy, Mar 06 2018