cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A233557 Prime(k), where k is such that (1 + Sum_{i=1..k} prime(i)^17) / k is an integer.

Original entry on oeis.org

2, 3, 7, 13, 29, 37, 641, 853, 2143, 18059, 26417, 34283, 48539, 122597, 146539, 254831, 8304757, 19534651, 26528699, 32820527, 47825363, 82199141, 124088207, 312168289, 409464961, 464174839, 1167927947, 1393486043, 1725361103, 1879982849, 4346448019, 7331901341, 7451088943, 27036461983, 39662532977, 113692593373, 449281234057
Offset: 1

Views

Author

Robert Price, Dec 12 2013

Keywords

Comments

a(45) > 491952295618219. - Bruce Garner, Jun 02 2021

Examples

			13 is a term because 13 is the 6th prime and the sum of the first 6 primes^17+1 = 9156096341463343272 when divided by 6 equals 1526016056910557212 which is an integer.
		

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

  • Mathematica
    t = {}; sm = 1; Do[sm = sm + Prime[n]^17; If[Mod[sm, n] == 0, AppendTo[t, Prime[n]]], {n, 100000}]; t (* Derived from A217599 *)
    With[{nn=175*10^8},Prime[#]&/@Select[Thread[{Range[nn],Accumulate[ Prime[ Range[nn]]^17]}],Divisible[#[[2]]+1,#[[1]]]&][[All,1]]] (* The program will take a long time to run *) (* Harvey P. Dale, Apr 13 2018 *)
  • PARI
    is(n)=if(!isprime(n),return(0)); my(t=primepi(n),s); forprime(p=2,n,s+=Mod(p,t)^17); s==0 \\ Charles R Greathouse IV, Nov 30 2013