This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A045345 Numbers n such that n divides sum of first n primes A007504(n). 118
 1, 23, 53, 853, 11869, 117267, 339615, 3600489, 96643287, 2664167025, 43435512311, 501169672991, 745288471601 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(10) and a(11) were found by Giovanni Resta (Nov 15 2004). He states that there are no other terms for primes p < 4011201392413. See link to Prime Puzzles, Puzzle 31 below. - Alexander Adamchuk, Aug 21 2006 a(13) > pi(2*10^13). - Donovan Johnson, Aug 23 2010 LINKS Javier Cilleruelo and Florian Luca, On the sum of the first n primes, Q. J. Math. 59:4 (2008), 14 pp. Kaisa MatomÃ¤ki, A note on the sum of the first n primes, Quart. J. Math. 61 (2010), pp. 109-115. The Prime Puzzles & Problems Connection: Puzzle 31.- The Average Prime number, APN(k) = S(Pk)/k. Eric Weisstein's World of Mathematics, Prime Sums OEIS wiki, Sums of powers of primes divisibility sequences. FORMULA MatomÃ¤ki proves that a(n) >> n^(24/19). - Charles R Greathouse IV, Jun 13 2012 EXAMPLE 23 is in the sequence because the sum of the first 23 primes is 874 and that's 23 * 38. 53 is in the sequence because the sum of the first 53 primes is 5830 and that's 53 * 110. 83 is not in the sequence because the sum of the first 83 primes is 15968, which leaves a remainder of 32 when divided by 83. MAPLE with(numtheory); ListA045345:=proc(q) local k, n; for n from 1 to q do if add(ithprime(k), k=1..n) mod n=0 then print(n); fi; od; end: ListA045345(10^12); # Paolo P. Lava, Jun 27 2013 MATHEMATICA s = 0; t = {}; Do[s = s + Prime[n]; If[ Mod[s, n] == 0, AppendTo[t, n]], {n, 1000000}]; t (* Alexander Adamchuk, Aug 21 2006 *) nn = 4000000; With[{acpr = Accumulate[Prime[Range[nn]]]}, Select[Range[nn], Divisible[acpr[[#]], #] &]] (* Harvey P. Dale, Sep 14 2012 *) Select[Range[100], Mod[Sum[Prime[i], {i, #}], #] == 0 &] (* Alonso del Arte, Mar 22 2014 based on Bill McEachen's Wolfram Alpha example *) PROG (PARI) s=0; n=0; forprime(p=2, 1e7, s+=p; if(s%n++==0, print1(n", "))) \\ Charles R Greathouse IV, Jul 15 2011 CROSSREFS Sequence in context: A078854 A078959 A238854 * A133986 A103006 A053236 Adjacent sequences:  A045342 A045343 A045344 * A045346 A045347 A045348 KEYWORD nonn,nice,more AUTHOR EXTENSIONS More terms from Alexander Adamchuk, Aug 21 2006 a(12) from Donovan Johnson, Aug 23 2010 a(13) from Robert Price, Mar 17 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.

Last modified January 20 16:44 EST 2019. Contains 319335 sequences. (Running on oeis4.)