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.

Showing 1-1 of 1 results.

A262807 a(n) = (Product_{k=1..n} prime(k+1)) mod (Sum_{k=1..n} prime(k+1)) where prime(k) is the k-th prime number.

Original entry on oeis.org

0, 7, 0, 11, 0, 7, 45, 91, 24, 55, 0, 113, 93, 175, 308, 153, 414, 395, 273, 355, 609, 779, 558, 23, 0, 843, 962, 185, 0, 547, 1634, 21, 170, 1149, 1455, 2483, 1830, 2275, 2865, 1989, 0, 1515, 1211, 2013, 1105, 403, 2733, 819, 0, 4011, 0, 1457, 4278, 1155, 391, 1717, 2596, 2163, 0, 5985
Offset: 1

Views

Author

Altug Alkan, Oct 02 2015

Keywords

Comments

Remainder when product of first n odd primes is divided by sum of first n odd primes.
Obviously a(2n) cannot be 0. Does 0 appear in the sequence infinitely often?

Examples

			a(1) = prime(2) mod prime(2) = 3 mod 3 = 0.
a(2) = (prime(2) * prime(3)) mod (prime(2) + prime(3)) = 15 mod 8 = 7.
a(3) = (prime(2) * prime(3) * prime(4)) mod (prime(2) + prime(3) + prime(4)) = 105 mod 15 = 0.
a(4) = (prime(2) * prime(3) * prime(4) * prime(5)) mod (prime(2) + prime(3) + prime(4) + prime(5)) = 1155 mod 26 = 11.
		

Crossrefs

Programs

  • Mathematica
    Table[Mod[Product[Prime[k + 1], {k, n}], Sum[Prime[k + 1], {k, n}]], {n, 60}] (* Michael De Vlieger, Oct 02 2015 *)
  • PARI
    a(n) = prod(k=1, n, prime(k+1)) % sum(k=1, n, prime(k+1));
    vector(60, n, a(n))

Formula

a(n) = A070826(n+1) mod A071148(n).
Showing 1-1 of 1 results.