A202105 Numbers k such that 90*k + 43 is prime.

0, 2, 3, 7, 9, 11, 12, 13, 14, 16, 18, 19, 21, 23, 24, 25, 26, 27, 31, 37, 38, 40, 41, 42, 44, 45, 47, 48, 52, 53, 54, 55, 60, 62, 67, 68, 70, 74, 75, 76, 80, 81, 84, 87, 88, 89, 91, 98, 100, 101, 104, 114, 118, 119, 123, 126, 130, 131, 132, 137, 139, 142

Offset: 1

Author

J. W. Helkenberg, Dec 11 2011

Keywords

• easy
• nonn
• changed

Comments

This sequence was generated by adding 12 Fibonacci-like sequences [See: PROG]. Looking at the format 90k+43 modulo 9 and modulo 10 we see that all entries of A142334 have digital root 7 and last digit 3. (Reverting the process is an application of the Chinese remainder theorem.) The 12 Fibonacci-like sequences are generated (via the p and q values given in the PERL program) from the base p,q pairs 43*91, 19*7, 37*79, 73*61, 11*53, 29*17, 47*89, 83*71, 13*31, 49*67, 23*41, 59*77.

Crossrefs

Cf. A181732, A198382, A195993, A196000, A196007, A201739, A201734, A201804, A201816, A201817, A201818, A201820, A201822, A202101, A202104.

Programs

Mathematica

Select[Range[0, 200], PrimeQ[90 # + 43] &]

PARI

is(n)=isprime(90*n+43) \\ Charles R Greathouse IV, Feb 17 2017