A202129 Numbers n such that 90n + 71 is prime.

0, 2, 4, 5, 7, 9, 10, 11, 12, 16, 17, 20, 23, 26, 28, 31, 33, 35, 38, 39, 40, 41, 42, 46, 48, 49, 52, 54, 55, 59, 60, 62, 63, 66, 67, 72, 76, 77, 82, 83, 87, 89, 90, 101, 103, 104, 105, 108, 111, 112, 114, 117, 118, 119, 125, 126, 129, 133, 137, 138, 140

Offset: 1

Author

J. W. Helkenberg, Dec 11 2011

Keywords

• nonn
• easy

Comments

This sequence was generated by adding 12 Fibonacci-like sequences [See: PROG?]. Looking at the format 90n+71 modulo 9 and modulo 10 we see that all entries of A142325 have digital root 8 and last digit 1. (Reverting the process is an application of the Chinese remainder theorem.) The 12 Fibonacci-like sequences are generated (via the p and q "seed" values entered into the Perl program) from the base p,q pairs 71*91, 19*89, 37*53, 73*13, 11*31, 29*49, 47*13, 83*67, 23*7, 41*61, 59*79, 77*43.

Crossrefs

Cf. A181732, A198382, A195993, A196000, A196007, A201739, A201734, A201804, A201816, A201817, A201818, A201820, A201822, A202101, A202104, A202105, A202110, A202112, A202113, A202114, A202115, A202116.

Programs

Mathematica

Select[Range[0, 200], PrimeQ[90 # + 71] &]

PARI

is(n)=isprime(90*n+71) \\ Charles R Greathouse IV, Jun 13 2017