A226071 Numbers n such that triangular(n)+1 is a square and triangular(n)+2 is a prime.

0, 2, 5, 189, 3074, 218685

Offset

1,2

Comments

Subsequence of A006451 that contains the terms n such that triangular(n)+2 is prime.

a(7) is too large to include here (see b-file). - Max Alekseyev, Jan 30 2014

Links

Max Alekseyev, Table of n, a(n) for n = 1..12

Mathematica

Select[Range[0, 220000], IntegerQ[Sqrt[(#(#+1))/2+1]]&&PrimeQ[(#(#+1))/2+2]&] (* Harvey P. Dale, Mar 01 2023 *)

Prog

(C) // see A226069.

Crossrefs

Corresponding primes: A226069.

Roots of corresponding squares: A226070.

Cf. A226071-A226074.

Sequence in context: A124275 A013130 A111392 * A319143 A100366 A339313

Adjacent sequences: A226068 A226069 A226070 * A226072 A226073 A226074

Keyword

nonn

Author

Alex Ratushnyak, May 25 2013

Extensions

Terms a(7)-a(12) from Max Alekseyev, Jan 30 2014

Status

approved