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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
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OFFSET
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1,2
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REFERENCES
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J. Sandor and B. Crstici, Handbook of Number Theory II, Springer, 2004, p. 265, eq. 10.
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LINKS
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Enrique Pérez Herrero, Table of n, a(n) for n = 1..200
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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! * Product_{p<n} (1-p)^floor(n/p) where the product runs through the primes. - Benoit Cloitre, Jan 31 2008
a(n) = A000142(n) * A085542(n). - Enrique Pérez Herrero, Jun 08 2010
a(n) = A001088(n) * A048803(n) * (-1)^A013939(n). - Amiram Eldar, Dec 19 2018
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MAPLE
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A060238:=n->n!*mul((1-ithprime(i))^floor(n/ithprime(i)), i=1..numtheory[pi](n)): seq(A060238(n), n=1..20); # Wesley Ivan Hurt, Aug 15 2016
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MATHEMATICA
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A060238[n_]:=n!*Product[(1 - Prime[i])^Floor[n/Prime[i]], {i, PrimePi[n]}]; Array[A060238, 20] (* Enrique Pérez Herrero, Jun 08 2010 *)
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PROG
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(PARI) a(n)=n!*prod(p=1, sqrtint(n), if(isprime(p), (1-p)^floor(n/p), 1)) \\ Benoit Cloitre, Jan 31 2008
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CROSSREFS
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Cf. A000142, A001088, A013939, A023900, A048803, A060239, A085542.
Sequence in context: A277183 A052588 A139239 * A085495 A119978 A139234
Adjacent sequences: A060235 A060236 A060237 * 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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STATUS
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approved
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