The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A280246 a(n) = Product_{d|n} psi(d), where psi(m) is the sum of totatives of m (A023896). 2
 1, 1, 3, 4, 10, 18, 21, 64, 81, 200, 55, 1728, 78, 882, 1800, 4096, 136, 26244, 171, 64000, 7938, 6050, 253, 2654208, 2500, 12168, 19683, 592704, 406, 25920000, 465, 1048576, 54450, 36992, 88200, 544195584, 666, 58482, 109512, 327680000, 820, 504094752, 903 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) = n only for n = 1, 3 and 4. n divides a(n) for all n except 2. Conjecture: a(n) is odd iff the sum of totatives of n (A023896) is odd. LINKS Table of n, a(n) for n=1..43. FORMULA a(n) = Product_{d|n} A023896(d). EXAMPLE For n=6; sets of totatives of divisors of 6: {1}, {1}, {1, 2}, {1, 5}; a(6) = 1*1*(1+2)*(1+5) = 18. MATHEMATICA Table[Product[Total@ Select[Range@ d, CoprimeQ[d, #] &], {d, Divisors@ n}], {n, 43}] (* Michael De Vlieger, Dec 30 2016 *) PROG (Magma) [&*[&+[h: h in [1..d] | GCD(h, d) eq 1]: d in Divisors(n)]: n in [1..100]] CROSSREFS Cf. A023896, A057661, A280247, A280248. Sequence in context: A337089 A144958 A034775 * A338012 A350042 A006490 Adjacent sequences: A280243 A280244 A280245 * A280247 A280248 A280249 KEYWORD nonn AUTHOR Jaroslav Krizek, Dec 30 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 26 04:29 EDT 2023. Contains 365653 sequences. (Running on oeis4.)