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A090220
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Denominators used in A090219 to compute formula for column sequences of array A078741.
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1
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1, 1, 1, 1, 2, 10, 20, 70, 560, 1680, 2800, 30800, 369600, 800800, 11211200, 168168000, 448448000, 7623616000, 137225088000, 434546112000, 8690922240000, 182509367040000, 669201012480000, 15391623287040000, 369398958888960000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,5
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COMMENTS
| The corresponding numerator sequence is N(n) := [1, 6, 3, 1, 3, 3, 1, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] for n=1..26.
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FORMULA
| a(n)= LCM(seq(denominator(a(n+2, m))), m=1..n)), with the a(n, m) formula of A090219(n, m) but without the 1/b(n-2) factor and LMC denotes the least common multiple of a set of numbers.
N(n) := GCD(seq(numerator(a(n+2, m))), m=1..n)), with the a(n, m) formula of A090219(n, m) but without the 1/b(n-2) factor and GCD denotes the greatest common divisor>1 of a set of numbers.
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EXAMPLE
| The fifth (k=7) column of A078741 needs in A090219 the factor b(5) := N(5)/a(5)= 3/2.
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CROSSREFS
| Sequence in context: A165551 A139592 A120552 * A164882 A029994 A004643
Adjacent sequences: A090217 A090218 A090219 * A090221 A090222 A090223
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KEYWORD
| nonn,easy
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AUTHOR
| Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Dec 01 2003
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