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A059377 Jordan function J_4(n). 23
1, 15, 80, 240, 624, 1200, 2400, 3840, 6480, 9360, 14640, 19200, 28560, 36000, 49920, 61440, 83520, 97200, 130320, 149760, 192000, 219600, 279840, 307200, 390000, 428400, 524880, 576000, 707280, 748800, 923520, 983040, 1171200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This sequence is multiplicative. - Mitch Harris, Apr 19 2005

REFERENCES

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 199, #3.

R. Sivaramakrishnan, "The many facets of Euler's totient. II. Generalizations and analogues", Nieuw Arch. Wisk. (4) 8 (1990), no. 2, 169-187.

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

FORMULA

a(n) = sum(d|n, d^4*mu(n/d)). - Benoit Cloitre, Apr 05 2002

Multiplicative with a(p^e) = p^(4e)-p^(4(e-1)).

Dirichlet generating function: zeta(s-4)/zeta(s). - Franklin T. Adams-Watters, Sep 11 2005

a(n) = Sum_{k=1..n} GCD(k,n)^4 * Cos(2*Pi*k/n). - Enrique Pérez Herrero, Jan 18 2013

MAPLE

J := proc(n, k) local i, p, t1, t2; t1 := n^k; for p from 1 to n do if isprime(p) and n mod p = 0 then t1 := t1*(1-p^(-k)); fi; od; t1; end; # (with k = 4)

MATHEMATICA

JordanJ[n_, k_: 1] := DivisorSum[n, #^k*MoebiusMu[n/#] &]; f[n_] := JordanJ[n, 4]; Array[f, 38]

PROG

(PARI) for(n=1, 100, print1(sumdiv(n, d, d^4*moebius(n/d)), ", "))

(PARI) a(n)=if(n<1, 0, sumdiv(n, d, d^4*moebius(n/d)))

(PARI) a(n)=if(n<1, 0, dirdiv(vector(n, k, k^4), vector(n, k, 1))[n])

(PARI) { for (n = 1, 1000, write("b059377.txt", n, " ", sumdiv(n, d, d^4*moebius(n/d))); ) } [Harry J. Smith, Jun 26 2009]

CROSSREFS

See A059379 and A059380 (triangle of values of J_k(n)), A000010 (J_1), A059376 (J_3), A059377 (J_4), A059378 (J_5).

See A059379 and A059380 (triangle of values of J_k(n)), A000010 (J_1), A007434 (J_2), A059376 (J_3), A059378 (J_5).

Sequence in context: A085808 A180577 A033594 * A123865 A024002 A050149

Adjacent sequences:  A059374 A059375 A059376 * A059378 A059379 A059380

KEYWORD

nonn,mult

AUTHOR

N. J. A. Sloane, Jan 28 2001

STATUS

approved

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Last modified April 19 14:25 EDT 2014. Contains 240761 sequences.