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 A321613 Partial products of the unitary totient function (A047994): a(n) = Product_{k=1..n} uphi(k). 1
 1, 1, 2, 6, 24, 48, 288, 2016, 16128, 64512, 645120, 3870720, 46448640, 278691840, 2229534720, 33443020800, 535088332800, 4280706662400, 77052719923200, 924632639078400, 11095591668940800, 110955916689408000, 2441030167166976000, 34174422340337664000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) is also the determinant of the symmetric n X n matrix M defined by M(i,j) = ugcd(i,j) for 1 <= i,j <= n, where ugcd(i,j) in the greatest common unitary divisor of i and j (A165430). The unitary version of A001088. LINKS Amiram Eldar, Table of n, a(n) for n = 1..481 H. Jager, The unitary analogues of some identities for certain arithmetical functions, Nederl. Akad. Wetensch. Proc. Ser. A, Vol. 64 (1961), pp. 508-515. EXAMPLE a(4) = uphi(1) * uphi(2) * uphi(3) * uphi(4) = 1 * 1 * 2 * 3 = 6. MATHEMATICA uphi[1] = 1; uphi[n_] := Times @@ (-1 + Power @@@ FactorInteger[n]); FoldList[ Times, uphi /@ Range[50]] PROG (PARI) uphi(n) = my(f=factor(n)~); prod(i=1, #f, f[1, i]^f[2, i]-1); \\ A047994 a(n) = prod(k=1, n, uphi(k)); \\ Michel Marcus, Dec 19 2018 CROSSREFS Cf. A001088, A047994, A165430, A177754. Sequence in context: A354216 A189851 A189563 * A104114 A175624 A289161 Adjacent sequences: A321610 A321611 A321612 * A321614 A321615 A321616 KEYWORD nonn AUTHOR Amiram Eldar, Dec 19 2018 STATUS approved

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Last modified June 13 17:32 EDT 2024. Contains 373391 sequences. (Running on oeis4.)