A141780 Numbers n such that A120292(n) is prime.

1, 4, 6, 10, 11, 12, 13, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 32, 33, 36, 37, 38, 40, 42, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 57, 59, 60, 61, 62, 63, 64, 65, 68, 69, 72, 73, 74, 76, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 93, 94, 95, 99, 100, 102

Offset: 1

Author

Alexander Adamchuk, Jul 04 2008

Keywords

• nonn

Crossrefs

Cf. A120292 = absolute value of the numerator of the determinant of n X n matrix M with M[i, j] = prime[i]/(1 + prime[i]) if i = j, and 1 otherwise.

Cf. A125716 = numbers n such that A120292(n) = 1.

Cf. A141779 = numbers n such that A120292(n) > 1 and is not prime.

Cf. A141781 = terms of A120292 that are greater than 1 and are not prime; or A120292(A141779).

Programs

Mathematica

Select[Range[200],PrimeQ[Numerator[Abs[(1 - Sum[Prime[k] + 1,{k, 1, #}])/Product[Prime[k] + 1, {k, 1, #}] ]]]&]

PARI

isok(n) = isprime(abs(numerator(matdet(matrix(n, n, i, j, if(i==j, prime(i)/(1+prime(i)), 1)))))); \\ Michel Marcus, May 10 2020