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Main diagonal of A284993.
4

%I #25 Oct 24 2018 02:33:31

%S 1,-1,-3,-20,-54,4935,403432,23308238,-2635805834,-2939783620152,

%T -1713742918458426,602896713529233651,9901041507182530035347,

%U 52279007840299710266340246,-71905380320280305597098525356,-17521448585729172053338909789657052

%N Main diagonal of A284993.

%H Seiichi Manyama, <a href="/A281268/b281268.txt">Table of n, a(n) for n = 0..80</a>

%F a(n) = [x^n] Product_{k=1..n} 1/(1 + x^k)^(k^n). - _Ilya Gutkovskiy_, Mar 06 2018

%o (Ruby)

%o def s(k, n)

%o s = 0

%o (1..n).each{|i| s += (-1) ** (n / i + 1) * i ** k if n % i == 0}

%o s

%o end

%o def A(k, n)

%o ary = [1]

%o a = [0] + (1..n).map{|i| s(k + 1, i)}

%o (1..n).each{|i| ary << (1..i).inject(0){|s, j| s - a[j] * ary[-j]} / i}

%o ary

%o end

%o def A281268(n)

%o (0..n).map{|i| A(i, i)[-1]}

%o end

%Y Cf. A284993.

%K sign

%O 0,3

%A _Seiichi Manyama_, Apr 13 2017