cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A266265 Product of products of divisors of divisors of n.

Original entry on oeis.org

1, 2, 3, 16, 5, 216, 7, 1024, 81, 1000, 11, 2985984, 13, 2744, 3375, 1048576, 17, 34012224, 19, 64000000, 9261, 10648, 23, 63403380965376, 625, 17576, 59049, 481890304, 29, 19683000000000, 31, 34359738368, 35937, 39304, 42875, 4738381338321616896, 37, 54872
Offset: 1

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Author

Jaroslav Krizek, Dec 25 2015

Keywords

Comments

a(n) = Product_{d|n} A007955(d) where A007955(m) = product of divisors of m.
From G. C. Greubel, Dec 31 2015: (Start)
for n>=1: 10^3|a(10*n), 10^6|a(20*n), 10^9|a(30*n).
for n>=0: 10^6|a(60*n+50), 10^9|a(60*n+70). (End)

Examples

			For n = 6; with b(n) = A007955(n); a(6) = b(1)*b(2)*b(3)*b(6) = 1*2*3*36 = 216.
		

Crossrefs

Cf. A007955 (product of divisors of n), A175317 (sum of products of divisors of divisors of n), A206032 (product of sums of divisors of divisors of n).

Programs

  • Magma
    [&*[&*[b: b in Divisors(d)]: d in Divisors(n)]: n in [1..100]]
    
  • Maple
    A266265 := proc(n)
        mul( A007955(d),d=numtheory[divisors](n)) ;
    end proc:
    seq(A266265(n),n=1..10) ; # R. J. Mathar, Feb 13 2019
  • Mathematica
    Table[Product[Times @@ Divisors@ d, {d, Divisors@ n}], {n, 38}] (* Michael De Vlieger, Dec 31 2015 *)
  • PARI
    a(n) = {my(d = divisors(n)); prod(k=1, #d, dd = divisors(d[k]); prod(kk=1,#dd, dd[kk]));} \\ Michel Marcus, Dec 27 2015

Formula

a(p) = p for p = prime.
a(n) = Product_{d|n} d^tau(n/d). - Ridouane Oudra, Apr 09 2023