cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A202116 Numbers n such that 90n + 89 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 7, 8, 13, 15, 17, 18, 20, 21, 22, 25, 28, 29, 30, 31, 32, 36, 41, 44, 45, 46, 48, 51, 55, 58, 59, 62, 64, 65, 66, 69, 70, 72, 73, 77, 78, 83, 84, 86, 87, 88, 92, 97, 99, 105, 106, 107, 111, 112, 113, 116, 118, 119, 120, 121, 122, 123, 127, 129
Offset: 1

Views

Author

J. W. Helkenberg, Dec 11 2011

Keywords

Comments

This sequence was generated by adding 12 Fibonacci-like sequences [See: PROG?]. Looking at the format 90n+89 modulo 9 and modulo 10 we see that all entries of A142335 have digital root 8 and last digit 9. (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 89*91, 19*71, 37*17, 73*53, 11*49, 29*31, 47*67, 83*13, 23*43, 41*79, 59*61, 77*7.

Crossrefs

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

Programs

  • Mathematica
    Select[Range[0, 200], PrimeQ[90 # + 89] &]
  • PARI
    is(n)=isprime(90*n+89) \\ Charles R Greathouse IV, Jun 06 2017

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

Original entry on oeis.org

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

Views

Author

J. W. Helkenberg, Dec 11 2011

Keywords

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

A224855 Numbers n such that 90*n + 17 and 90*n + 19 are twin primes.

Original entry on oeis.org

0, 1, 2, 9, 14, 22, 23, 25, 35, 36, 39, 46, 48, 50, 53, 55, 60, 65, 77, 79, 81, 83, 86, 93, 98, 111, 116, 130, 148, 154, 165, 168, 189, 191, 193, 196, 197, 198, 203, 210, 226, 230, 231, 232, 246, 252, 256, 263, 281, 284, 287, 301, 308, 310, 312, 314, 317, 347
Offset: 1

Views

Author

J. W. Helkenberg, Jul 22 2013

Keywords

Comments

All matching entries for A202115 and A196000 are twin primes.

Links

Crossrefs

Cf. A202115, A196000.

Programs

  • Mathematica
    Select[Range[0, 499], PrimeQ[90# + 17] && PrimeQ[90# + 19] &] (* Copied from: Alonso del Arte, Jul 22 2013 *)
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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