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Search: id:A060238
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| A060238 |
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det(M) where M is an n X n matrix with M[i,j]=lcm(i,j). |
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+0
6
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| 1, -2, 12, -48, 960, 11520, -483840, 3870720, -69672960, -2786918400, 306561024000, 7357464576000, -1147764473856000, -96412215803904000, 11569465896468480000, 185111454343495680000
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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For n >= 2 a(n) = n! * product(j=2, ..., n)(product(p|j)(1-p)) (where the second product is over all primes p that divide j) [Cf. A023900] - Avi Peretz (njk(AT)netvision.net.il), Mar 22 2001
a(n)=n!*prod(p<n,(1-p)^floor(n/p)) where the product runs through the primes. - Benoit Cloitre (benoit7848c(AT)orange.fr), Jan 31 2008
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PROGRAM
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(PARI) a(n)=n!*prod(p=1, sqrtint(n), if(isprime(p), (1-p)^floor(n/p), 1)) - Benoit Cloitre (benoit7848c(AT)orange.fr), Jan 31 2008
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CROSSREFS
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Cf. A001088, A060239.
Sequence in context: A088311 A052588 A139239 this_sequence A085495 A119978 A139234
Adjacent sequences: A060235 A060236 A060237 this_sequence A060239 A060240 A060241
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KEYWORD
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sign
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AUTHOR
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MCKAY john (mckay(AT)cs.concordia.ca), Mar 21 2001
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