A335031 - OEIS

A335031

Complement of A334919.

1, 2, 3, 4, 6, 7, 10, 11, 12, 14, 15, 19, 20, 22, 24, 26, 27, 31, 32, 34, 35, 36, 39, 42, 46, 47, 50, 52, 54, 55, 59, 60, 64, 66, 67, 70, 71, 74, 75, 76, 80, 87, 90, 91, 92, 94, 99, 102, 104, 110, 111, 112, 115, 116, 119, 122, 124, 126, 127, 131, 132, 136

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OFFSET

1,2

COMMENTS

For each term m belonging to this list, 3*m+1 or (3*m+1)/2 is a prime.

LINKS

Table of n, a(n) for n=1..62.

EXAMPLE

1, 2, 3, 4, are terms because for i,j >= 1, number 3*i*j+i+j >= 5, and for i,j >= 2, number 3*i*j-i-j >= 8.

PROG

(Magma) [m:m in [1..140]|not exists(a){i:i in [1..m-1]|IsIntegral((m-i)/(1+3*i))} and not exists(b){j:j in [2..m-1]|IsIntegral((m+j)/(-1+3*j)) and (m+j)/(-1+3*j) ge 2}]; // Marius A. Burtea, Jun 04 2020

CROSSREFS

Cf. A334919.

Sequence in context: A375928 A287531 A047518 * A179834 A352335 A361798

Adjacent sequences: A335028 A335029 A335030 * A335032 A335033 A335034

KEYWORD

nonn

AUTHOR

Davide Rotondo, May 20 2020

STATUS

approved