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 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 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

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