A133291 a(n) = m such that t(n) +/- m are +-primes, where t(n) = n(n+1)/2.

4, 8, 11, 13, 22, 26, 31, 43, 52, 58, 61, 71, 72, 74

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Example

1-4=-3,1+4=5; 3-8=-5,3+8=11; 6-11=-5,6+11=17;

Mathematica

a = 0; y = 0; For[i = 1, i < 15, a = a + i; Do[If[PrimeQ[a - k] && PrimeQ[a + k] && k > y, y = k; Break[]], {k, 250}]; Print[a, ": ", a - y, ", ", y, ", ", a + y]; i++ ]

Crossrefs

Sequence in context: A311028 A311029 A026999 * A356105 A311030 A311031

Adjacent sequences: A133288 A133289 A133290 * A133292 A133293 A133294

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Oct 17 2007

Status

approved