login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A273290 A273288(n)^Omega(n), where Omega = A001222. 4
2, 3, 4, 5, 4, 7, 8, 9, 9, 11, 8, 13, 9, 9, 16, 17, 27, 19, 8, 25, 25, 23, 16, 25, 49, 27, 8, 29, 27, 31, 32, 49, 49, 25, 16, 37, 49, 49, 16, 41, 27, 43, 8, 27, 121, 47, 32, 49, 125, 49, 8, 53, 81, 49, 16, 121, 169, 59, 16, 61, 169, 27, 64, 49, 27, 67, 8, 169, 125 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

a(n) is by definition the power of a prime. It coincides with n iff n is the power of a prime (A246655).

a(n) <= A273291(n)

LINKS

Giuseppe Coppoletta, Table of n, a(n) for n = 2..10000

FORMULA

a(n) = A273288(n)^A001222(n).

EXAMPLE

a(70) = A273291(70) = 5^3 because the median  of its prime factors [2, 5, 7] is the central value 5 (prime) and Omega(70)=3.

a(308) = 3^4 because Omega(308)=4 and the median of [2, 2, 7, 11] is (2+7)/2 = 4.5, whose previous prime is 3.

MATHEMATICA

Table[Prime[PrimePi@ Median@ #]^Length@ # &@ Flatten@ Apply[Table[#1 {#2}] &, FactorInteger@ n, 1], {n, 2, 75}] (* Michael De Vlieger, May 27 2016 *)

PROG

(Sage) def pfwr(n): return flatten([([p] * m) for (p, m) in factor(n)]) # (list of prime factors of n with repetition)

[previous_prime(floor(median(pfwr(n)))+1)^sloane.A001222(n) for n in (2..70)]

CROSSREFS

Cf. A273284, A273288, A273291, A079867, A246655, A001222.

Sequence in context: A074882 A273284 A079867 * A079869 A200322 A075054

Adjacent sequences:  A273287 A273288 A273289 * A273291 A273292 A273293

KEYWORD

nonn

AUTHOR

Giuseppe Coppoletta, May 25 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 17 11:14 EDT 2019. Contains 326057 sequences. (Running on oeis4.)