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Search: id:A061553
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| A061553 |
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Sum of absolute values of coefficients of expansion of (1-x)(1-x^2)(1-x^3)...(1-x^n). |
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+0
1
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| 1, 2, 4, 6, 8, 12, 16, 20, 28, 36, 44, 54, 72, 92, 104, 138, 176, 212, 268, 332, 416, 508, 628, 776, 968, 1192, 1480, 1836, 2288, 2812, 3472, 4292, 5312, 6572, 8120, 10028, 12388, 15300, 18860, 23276, 28740, 35468, 43732, 53954, 66540, 82016, 101044
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OFFSET
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0,2
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FORMULA
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L(n) := |a(n, 0)| + |a(n, 1)| + ... + |a(n, n(n+1)/2)| where a(n, j) are the coefficients of the polynomial P(n, x) := (1-x)(1-x^2)(1-x^3)...(1-x^n)
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EXAMPLE
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L(0) = 1; L(1) = 1+1 = 2; L(4) = Length(P(4,x)) = Length(1 - x - x^2 + 2x^5 - x^8 - x^9 + x^10) = 1+1+1+2+1+1+1 = 8
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CROSSREFS
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Adjacent sequences: A061550 A061551 A061552 this_sequence A061554 A061555 A061556
Sequence in context: A036912 A097921 A117146 this_sequence A138934 A008764 A065386
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KEYWORD
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nonn
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AUTHOR
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Steffen Eckmann (steffen.eckmann(AT)eon.com), May 17 2001
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