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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A099636 a(n) = gcd(sum of distinct prime factors of n, product of distinct prime factors of n). 7
1, 2, 3, 2, 5, 1, 7, 2, 3, 1, 11, 1, 13, 1, 1, 2, 17, 1, 19, 1, 1, 1, 23, 1, 5, 1, 3, 1, 29, 10, 31, 2, 1, 1, 1, 1, 37, 1, 1, 1, 41, 6, 43, 1, 1, 1, 47, 1, 7, 1, 1, 1, 53, 1, 1, 1, 1, 1, 59, 10, 61, 1, 1, 2, 1, 2, 67, 1, 1, 14, 71, 1, 73, 1, 1, 1, 1, 6, 79, 1, 3, 1, 83, 6, 1, 1, 1, 1, 89, 10, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
From Antti Karttunen, Feb 01 2021: (Start)
a(n) = gcd(A007947(n), A008472(n)).
a(n) = A007947(n) / A340677(n) = A008472(n) / A340678(n).
(End)
EXAMPLE
n=84: a(84) = gcd(2*3*7, 2+3+7) = gcd(42, 12) = 6.
MATHEMATICA
PrimeFactors[n_Integer] := Flatten[ Table[ # [[1]], {1}] & /@ FactorInteger[n]]; f[n_] := Block[{pf = PrimeFactors[n]}, GCD[Plus @@ pf, Times @@ pf]]; Table[ f[n], {n, 93}] (* Robert G. Wilson v, Nov 04 2004 *)
PROG
(PARI)
A007947(n) = factorback(factorint(n)[, 1]); \\ From A007947
A008472(n) = vecsum(factor(n)[, 1]); \\ From A008472
A099636(n) = gcd(A007947(n), A008472(n));
CROSSREFS
Differs from related A099635 for the first time at n=84, where a(84) = 6, while A099635(84) = 12.
Differs from A014963 for the first time at n=30, where a(30) = 10, while A014963(30) = 1.
Sequence in context: A157753 A020500 A014963 * A099635 A178380 A178375
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 28 2004
EXTENSIONS
Name clarified by Antti Karttunen, Feb 01 2021
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 24 11:15 EST 2024. Contains 370303 sequences. (Running on oeis4.)