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A056972
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Heaps on n levels (i.e. of 2^n - 1 elements).
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1
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OFFSET
| 0,3
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COMMENTS
| A sequence {a_i}_{i=1}^N forms a (binary) heap if is satisfies a_i<a_{2i} and a_i<a_{2i+1} for 1<=i<=(N-1)/2
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LINKS
| Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
| There is 1 heap on 2^0-1=0 elements, 1 heap on 2^1-1=1 element and there are 2 heaps on 2^2-1=3 elements and so on.
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MAPLE
| a:=n->(2^n-1)!/product((2^k-1)^(2^(n-k)), k=1..n); seq(a(i), i=0..6); - Alois P. Heinz (heinz(AT)hs-heilbronn.de), Nov 22 2007
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MATHEMATICA
| s[1] := 1; s[l_] := s[l] := Binomial[2^l-2, 2^(l-1)-1]s[l-1]^2; Table[s[l], {l, 10}]
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CROSSREFS
| Cf. A056971.
Sequence in context: A008563 A059487 A156932 * A051391 A041799 A187858
Adjacent sequences: A056969 A056970 A056971 * A056973 A056974 A056975
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KEYWORD
| nonn
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AUTHOR
| Eric Weisstein (eric(AT)weisstein.com)
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