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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A045576 Numbers k that divide 3^k + 2^k. 7
 1, 5, 25, 55, 125, 275, 605, 625, 1375, 3025, 3125, 6655, 6875, 15125, 15625, 30025, 31375, 33275, 34375, 73205, 75625, 78125, 150125, 156875, 166375, 171875, 330275, 345125, 366025, 378125, 390625, 439835, 750625, 784375, 805255, 831875 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For any j>=0, 5*A003598(j) is a term of the sequence. - Benoit Cloitre, Mar 08 2002 From Robert Israel, Jun 29 2017: (Start) This is a semigroup: if m and n are in the sequence, then so is m*n. If n is in the sequence and is divisible by prime p, then so is p*n. The only prime power in the sequence is 5. Conjecture: Every member of the sequence except 1 is of the form p*m where p is prime and m is in the sequence. (End) LINKS Robert Israel and Giovanni Resta, Table of n, a(n) for n = 1..1000 (first 205 terms from Robert Israel) MAPLE select(t -> 3 &^ t + 2 &^ t mod t = 0, [seq(i, i=1..10^6, 2)]); # Robert Israel, Jun 29 2017 PROG (PARI) isok(n) = ((3^n+2^n) % n) == 0; \\ Michel Marcus, Jun 29 2017 (PARI) isok(n)=(Mod(2, n)^n+Mod(3, n)^n)==0; \\ significantly more efficient for(n=1, 10^6, if(isok(n), print1(n, ", "))); \\ Joerg Arndt, Aug 13 2017 CROSSREFS Cf. A003598, A007689. Sequence in context: A078569 A044082 A161143 * A146649 A326314 A273357 Adjacent sequences:  A045573 A045574 A045575 * A045577 A045578 A045579 KEYWORD nonn AUTHOR 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.

Last modified January 22 21:47 EST 2022. Contains 350504 sequences. (Running on oeis4.)