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A080202
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Triangle T(k,b) read by rows, giving numbers of pairs of unequal permutations of all the digits 1, ..., k in base b (k<b) whose ratio is an integer.
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1
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0, 0, 1, 0, 0, 1, 0, 0, 3, 25, 0, 0, 0, 2, 7, 0, 0, 0, 0, 68, 623, 0, 0, 0, 0, 0, 124, 1183, 0, 0, 0, 0, 0, 0, 2338, 24603, 0, 0, 0, 0, 0, 0, 3, 598, 5895, 0, 0, 0, 0, 0, 0, 0, 0, 161947, 2017603
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 3,9
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COMMENTS
| Terms computed by Michael Trott.
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LINKS
| Eric Weisstein's World of Mathematics, Steffi Problem
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EXAMPLE
| Triangle is arranged as (b,k) = (3, 2), (4, 2), (4, 3), (5, 2), (5, 3), (5,4), (6,2), ....
In base 3, there are no solutions for 12, so a(1)=0. In base 4, there are no solutions for 12, so a(2)=0 and a single solution for 123, so a(3)=1. In base 5, there are no solutions with the digits 12 or 123, so a(4)=a(5)=0, but there is a single solution with the digits 1234: 4312_5/1234_5 = 3, so a(6)=1.
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CROSSREFS
| T(b-1, b) gives A080203.
Sequence in context: A000856 A047678 A047938 * A085836 A073916 A076962
Adjacent sequences: A080199 A080200 A080201 * A080203 A080204 A080205
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KEYWORD
| nonn,tabl
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AUTHOR
| Eric Weisstein (eric(AT)weisstein.com), Feb 05, 2003
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