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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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6
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1, -2, 12, -48, 960, 11520, -483840, 3870720, -69672960, -2786918400, 306561024000, 7357464576000, -1147764473856000, -96412215803904000, -11569465896468480000, 185111454343495680000, -50350315581430824960000, -1812611360931509698560000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Enrique Pérez Herrero, Table of n, a(n) for n = 1..200
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FORMULA
| 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
a(n)=A000142(n)*A085542(n) [From Enrique Perez Herrero (psychgeometry(AT)gmail.com), Jun 08 2010]
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MATHEMATICA
| A060238 [n_]:=n!*Product[(1 - Prime[i])^Floor[n/Prime[i]], {i, 1, PrimePi[n]}]; [From Enrique Perez Herrero (psychgeometry(AT)gmail.com), Jun 08 2010]
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PROG
| (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
| Cf. A001088, A060239.
Sequence in context: A088311 A052588 A139239 * A085495 A119978 A139234
Adjacent sequences: A060235 A060236 A060237 * A060239 A060240 A060241
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KEYWORD
| sign
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AUTHOR
| MCKAY john (mckay(AT)cs.concordia.ca), Mar 21 2001
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