A106155 Numbers k > 2 such that prime(k)# + (prime(k+1))^2 or prime(k+1)# - (prime(k+2))^2 is prime or both are primes.

3, 4, 5, 6, 7, 10, 12, 13, 19, 26, 28, 41, 66, 73, 76, 78, 85, 371, 437, 513, 661, 726, 924, 1063, 1331, 1380, 1422, 1602, 1947, 1963, 3091, 3295, 3401

Offset

1,1

Links

Table of n, a(n) for n=1..33.

Example

2*3*5 + 7*7 = 79 prime as 2*3*5*7 - 11*11 = 89 prime so a(1)=3.
2*3*5*7 + 11*11 = 331 prime as 2*3*5*7*11 -13*13 = 2141 prime so a(2)=4.
2*3*5*7*11 + 13*13 = 2479 = 37*67 composite.
2*3*5*7*11*13 - 17*17 = 29471 prime so a(3)=5.

Crossrefs

Cf. A002110, A038767.

Sequence in context: A159973 A359772 A158008 * A271376 A087190 A085038

Adjacent sequences: A106152 A106153 A106154 * A106156 A106157 A106158

Keyword

more,nonn

Author

Pierre CAMI, May 08 2005

Extensions

a(20)-a(30) from Donovan Johnson, Apr 27 2008

a(31)-a(33) from Michael S. Branicky, Jun 09 2023

Status

approved