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A281268
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Main diagonal of A284993.
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4
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1, -1, -3, -20, -54, 4935, 403432, 23308238, -2635805834, -2939783620152, -1713742918458426, 602896713529233651, 9901041507182530035347, 52279007840299710266340246, -71905380320280305597098525356, -17521448585729172053338909789657052
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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LINKS
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FORMULA
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a(n) = [x^n] Product_{k=1..n} 1/(1 + x^k)^(k^n). - Ilya Gutkovskiy, Mar 06 2018
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PROG
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(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
(0..n).map{|i| A(i, i)[-1]}
end
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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