A073272 A000040(n+1) - A073271(n).

0, 1, 0, 3, -1, 3, -1, 0, 5, -3, 3, 3, -1, -1, 1, 5, -3, 3, 3, -3, 3, -1, -1, 5, 3, -1, 3, -1, -9, 11, -1, 5, -7, 9, -3, 1, 3, -1, 1, 5, -7, 9, -1, 3, -9, 1, 9, 3, -1, -1, 5, -7, 5, 1, 1, 5, -3, 3, 3, -7, -3, 11, 3, -1, -9, 9, -3, 9, -1, -1, -1, 3, 1, 3, -1, -1, 5, -3, -1, 9, -7, 9, -3, 3, -1

Offset

1,4

Comments

Observation/conjecture: a(n)=0 iff A073271(n) in {3, 7, 23}.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

For n=11, A000040(11)*A000040(13)/A000040(12) = 31*41/37 = 1271/37 = (34*37+13)/37, therefore A073271(11)=34; a(11) = A000040(12)-A073271(11) = 37-34 = +3.

Mathematica

Table[Prime[n+1] - Floor[Prime[n] Prime[n+2] / Prime[n+1]], {n, 80}] (* Vincenzo Librandi, May 31 2015 *)

Prog

(Magma) [NthPrime(n+1)-Floor(NthPrime(n)*NthPrime(n+2) / NthPrime(n+1)): n in [1..80]]; // Vincenzo Librandi, May 31 2015
(PARI) a(n, p=prime(n))=my(q=nextprime(p+1), r=nextprime(q+1)); q - p*r\q \\ Charles R Greathouse IV, Jun 02 2015

Crossrefs

Cf. A073274.

Sequence in context: A156872 A263526 A132301 * A268442 A175623 A121273

Adjacent sequences: A073269 A073270 A073271 * A073273 A073274 A073275

Keyword

sign

Author

Reinhard Zumkeller, Jul 22 2002

Status

approved