A089965 Both n + 1 and n/2 + 1 are primes.

2, 4, 12, 36, 60, 72, 156, 192, 276, 312, 396, 420, 456, 540, 612, 660, 672, 732, 756, 876, 996, 1092, 1152, 1200, 1212, 1236, 1320, 1380, 1452, 1620, 1656, 1752, 1872, 1932, 1992, 2016, 2136, 2340, 2472, 2556, 2592, 2796, 2856, 2916, 3060, 3216, 3252

Offset

1,1

Links

Table of n, a(n) for n=1..47.

Formula

a(n) = A005383(n)-1. - Robert Israel, Dec 13 2018

Mathematica

Select[Range[5*10^3], PrimeQ[ # + 1] && PrimeQ[ #/2 + 1] &]

Crossrefs

Cf. A005383.

Sequence in context: A334250 A211768 A112083 * A202727 A325255 A084716

Adjacent sequences: A089962 A089963 A089964 * A089966 A089967 A089968

Keyword

nonn

Author

Joseph L. Pe, Jan 18 2004

Status

approved