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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A175787 Primes together with 4. 3
2, 3, 4, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

sopf(n) is the sum of the distinct primes dividing n (A008472). Because sopf(n) = n if n is prime, this sequence is numbers n such that n^sopf(n) = sopf(n)^n.

Numbers n whose sum of prime factors is n. - Arkadiusz Wesolowski, Jan 17 2012

Numbers n such that 2n has exactly four divisors. - Wesley Ivan Hurt, Jul 01 2013

Numbers n such that n^2 does not divide n!. - Charles R Greathouse IV, Nov 04 2013

Numbers n such that n does not divide (n-1)!. - Elizabeth Axoy, Sep 24 2019

LINKS

Table of n, a(n) for n=1..60.

FORMULA

a(n) = A046022(n+1). - Omar E. Pol, Nov 27 2012

MAPLE

with(numtheory): digits:=200:nn:=200:for a from 1 to nn do: t1:=ifactors(a)[2]:t2:=sum(t1[i][1], i=1..nops(t1)) :if a^t2=t2^a then printf(`%d, `, a):else fi:od:

PROG

(PARI) a(n)=if(n>3, prime(n-1), n+1) \\ Charles R Greathouse IV, Aug 26 2011

CROSSREFS

Cf. A008472, A046022.

Sequence in context: A033070 A211781 A046022 * A073019 A174291 A007885

Adjacent sequences:  A175784 A175785 A175786 * A175788 A175789 A175790

KEYWORD

nonn,easy

AUTHOR

Michel Lagneau, Sep 04 2010

EXTENSIONS

Switched comment and name. Charles R Greathouse IV, Nov 04 2013

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 December 8 18:37 EST 2019. Contains 329865 sequences. (Running on oeis4.)