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A060238 det(M) where M is an n X n matrix with M[i,j] = lcm(i,j). 6
1, -2, 12, -48, 960, 11520, -483840, 3870720, -69672960, -2786918400, 306561024000, 7357464576000, -1147764473856000, -96412215803904000, -11569465896468480000, 185111454343495680000, -50350315581430824960000, -1812611360931509698560000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Enrique Pérez Herrero, Table of n, a(n) for n = 1..200

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! * 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]

MAPLE

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

MATHEMATICA

A060238[n_]:=n!*Product[(1 - Prime[i])^Floor[n/Prime[i]], {i, PrimePi[n]}]; Array[A060238, 20] (* Enrique Pérez Herrero, Jun 08 2010 *)

PROG

(PARI) a(n)=n!*prod(p=1, sqrtint(n), if(isprime(p), (1-p)^floor(n/p), 1)) - Benoit Cloitre, Jan 31 2008

CROSSREFS

Cf. A000142, A001088, A023900, A060239, A085542.

Sequence in context: A277183 A052588 A139239 * A085495 A119978 A139234

Adjacent sequences:  A060235 A060236 A060237 * A060239 A060240 A060241

KEYWORD

sign

AUTHOR

MCKAY john (mckay(AT)cs.concordia.ca), Mar 21 2001

STATUS

approved

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Last modified November 15 22:20 EST 2018. Contains 317252 sequences. (Running on oeis4.)