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 1-10 of 21 results. Next

A195993 Numbers n such that 90n + 73 is prime.

Original entry on oeis.org

0, 1, 4, 5, 6, 9, 11, 12, 15, 18, 19, 20, 22, 23, 27, 28, 29, 32, 36, 39, 40, 42, 43, 49, 51, 54, 55, 56, 61, 62, 63, 65, 70, 72, 74, 75, 85, 88, 91, 92, 93, 95, 96, 97, 98, 103, 104, 106, 109, 110, 113, 114, 116, 127, 128, 131
Offset: 1

Views

Author

J. W. Helkenberg, Oct 27 2011

Keywords

Comments

This sequence results from the propagation (addition) of 12 Fibonacci-like sequences; this sequence contains (recovers) all digital root 1 and last digit 3 prime numbers.

Crossrefs

Programs

  • Maple
    A142326 := proc(n)
            option remember;
            if n = 1 then
                    73 ;
            else
                    a := nextprime(procname(n-1)) ;
                    while (a mod 45) <> 28 do
                            a := nextprime(a) ;
                    end do;
                    return a;
            end if;
    end proc:
    A195993 := proc(n)
            (A142326(n)-73)/90 ;
    end proc:
    seq(A195993(n),n=1..80) ; # R. J. Mathar, Oct 31 2011
  • Mathematica
    Select[Range[0,200],PrimeQ[90#+73]&] (* Harvey P. Dale, May 05 2014 *)
  • PARI
    is(n)=isprime(90*n+73) \\ Charles R Greathouse IV, Apr 25 2016

Formula

a(n) = (A142326(n)-73)/90.

A196000 Numbers k such that 90*k + 19 is prime.

Original entry on oeis.org

0, 1, 2, 4, 8, 9, 10, 11, 14, 16, 17, 22, 23, 24, 25, 28, 30, 34, 35, 36, 39, 41, 43, 46, 48, 50, 53, 55, 56, 60, 63, 64, 65, 69, 74, 77, 78, 79, 80, 81, 83, 85, 86, 91, 93, 98, 99, 101, 102, 107, 108, 109, 111, 112, 115, 116
Offset: 1

Views

Author

J. W. Helkenberg, Oct 27 2011

Keywords

Comments

A142322 is a digital root 1 and last digit 9 preserving sequence.

Crossrefs

Programs

  • Maple
    A142322 := proc(n)
            option remember;
            if n = 1 then
                    19 ;
            else
                    a := nextprime(procname(n-1)) ;
                    while (a mod 45) <> 19 do
                            a := nextprime(a) ;
                    end do;
                    return a;
            end if;
    end proc:
    A196000 := proc(n)
            (A142322(n)-19)/90 ;
    end proc:
    seq(A196000(n),n=1..80) ; # R. J. Mathar, Oct 31 2011
  • Mathematica
    Select[Range[0, 120], PrimeQ[90 # + 19] &] (* Ivan Neretin, Apr 27 2017 *)
  • PARI
    is(n)=isprime(90*n+19) \\ Charles R Greathouse IV, Apr 25 2016

Formula

a(n) = (A142322(n) - 19)/90.

A196007 Numbers n such that 90n + 83 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 10, 12, 15, 16, 17, 21, 22, 23, 24, 25, 26, 29, 32, 36, 37, 39, 42, 45, 49, 50, 51, 54, 58, 59, 60, 61, 64, 67, 68, 71, 72, 73, 75, 77, 78, 79, 80, 84, 86, 89, 91, 92, 94, 101, 105, 106, 108, 112, 113, 114, 115, 117, 120
Offset: 1

Views

Author

J. W. Helkenberg, Oct 27 2011

Keywords

Crossrefs

Cf. A196000, A198382, A181732, A195993. These are digital root and last digit preserving sequences.

Programs

  • Maple
    A142332 := proc(n)
            option remember;
            if n = 1 then
                    83 ;
            else
                    a := nextprime(procname(n-1)) ;
                    while (a mod 45) <> 38 do
                            a := nextprime(a) ;
                    end do;
                    return a;
            end if;
    end proc:
    A196007 := proc(n)
            (A142332(n)-83)/90 ;
    end proc:
    seq(A196007(n),n=1..80) ; # R. J. Mathar, Oct 31 2011
  • Mathematica
    Select[Range[0, 120], PrimeQ[90 # + 83] &] (* Ivan Neretin, May 02 2017 *)
  • PARI
    is(n)=isprime(90*n+83) \\ Charles R Greathouse IV, Jul 12 2016

Formula

a(n) = (A142332(n)-83)/90.

A201734 Numbers n such that 90*n + 47 is prime.

Original entry on oeis.org

0, 1, 2, 3, 6, 7, 9, 10, 13, 14, 16, 18, 20, 22, 24, 25, 27, 29, 31, 32, 38, 39, 43, 44, 49, 50, 51, 53, 56, 63, 64, 65, 66, 69, 77, 80, 83, 84, 87, 90, 91, 95, 98, 101, 102, 105, 106, 107, 108, 109, 111, 116, 118, 120, 121, 122, 123, 129, 132, 134, 135, 137
Offset: 1

Views

Author

J. W. Helkenberg, Dec 04 2011

Keywords

Comments

A reverse reading of A142313; all entries of A142313 have digital root 2 and last digit 7.

Crossrefs

Programs

  • Magma
    [n: n in [0..200] | IsPrime(90*n+47)]; // Vincenzo Librandi, Dec 11 2011
    
  • Maple
    for n from 0 to 240 do
        p := 90*n+47 ;
        if isprime(p) then
            printf("%d,",n) ;
        end if;
    end do: # R. J. Mathar, Dec 05 2011
  • Mathematica
    Select[Range[0,400],PrimeQ[90 #+47]&] (* Vincenzo Librandi, Dec 11 2011 *)
  • PARI
    is(n)=isprime(90*n+47) \\ Charles R Greathouse IV, Feb 17 2017

Formula

a(n) = (A142313(n)-47)/90.

A201739 Numbers n such that 90*n + 29 is prime.

Original entry on oeis.org

0, 4, 5, 6, 7, 9, 10, 11, 12, 14, 17, 23, 27, 28, 30, 31, 32, 33, 34, 37, 38, 39, 41, 44, 45, 47, 48, 53, 54, 61, 65, 70, 73, 74, 75, 76, 77, 80, 83, 84, 88, 89, 91, 96, 98, 100, 102, 105, 108, 109, 110, 114, 117, 119, 125, 126, 128, 132, 136, 139, 142, 143
Offset: 1

Views

Author

J. W. Helkenberg, Dec 04 2011

Keywords

Comments

This sequence was generated by adding 12 Fibonacci-like sequences. Looking at the format 90n+29 modulo 9 and modulo 10 we see that all entries of A142327 have digital root 2 and last digit 9. (Reverting the process is an application of the Chinese remainder theorem.)

Crossrefs

Programs

  • Magma
    [n: n in [0..200] | IsPrime(90*n+29)]; // Vincenzo Librandi, Dec 11 2011
  • Maple
    for n from 0 to 240 do
        p := 90*n+29 ;
        if isprime(p) then
            printf("%d,",n) ;
        end if;
    end do: # R. J. Mathar, Dec 05 2011
  • Mathematica
    Select[Range[0,400],PrimeQ[90 #+29]&] (* Vincenzo Librandi, Dec 11 2011 *)
  • PARI
    forstep(n=29,1e4,90,if(isprime(n),print1(n\90", "))) \\ Charles R Greathouse IV, Dec 05 2011
    

Formula

a(n) = (A142327(n) - 29)/90.

A201804 Numbers k such that 90*k + 11 is prime.

Original entry on oeis.org

0, 1, 2, 3, 5, 7, 9, 10, 12, 13, 15, 16, 19, 20, 21, 23, 26, 27, 28, 29, 30, 31, 36, 41, 43, 47, 49, 52, 54, 56, 58, 61, 62, 65, 68, 69, 70, 72, 73, 75, 79, 80, 83, 87, 90, 92, 97, 98, 100, 103, 104, 105, 106, 112, 113, 114, 118, 124, 125
Offset: 1

Views

Author

J. W. Helkenberg, Dec 05 2011

Keywords

Comments

This sequence was generated by adding 12 Fibonacci-like sequences. Looking at 90*k+11 modulo 9 and modulo 10 we see that all entries of A142317 have digital root 2 and last digit 1. (Reverting the process is an application of the Chinese remainder theorem)

Crossrefs

Programs

Extensions

a(24)-a(59) from Vincenzo Librandi, Dec 11 2011

A201816 Numbers k such that 90*k + 13 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 8, 9, 12, 16, 17, 19, 22, 23, 30, 31, 35, 36, 37, 38, 40, 42, 46, 47, 49, 50, 51, 53, 58, 59, 60, 61, 63, 66, 67, 68, 74, 75, 80, 82, 84, 86, 88, 92, 95, 99, 100, 101, 103, 105, 107, 108, 112, 114, 116, 119, 121, 122, 123, 124, 126, 127
Offset: 1

Views

Author

J. W. Helkenberg, Dec 05 2011

Keywords

Comments

Looking at the format 90*k+13 modulo 9 and modulo 10 we see that all entries of A142318 have digital root 4 and last digit 3. (Reverting the process is an application of the Chinese remainder theorem.)

Crossrefs

Programs

  • Magma
    [n: n in [0..200] | IsPrime(90*n+13)]; // Vincenzo Librandi, Dec 12 2011
    
  • Maple
    a:= proc(n) option remember; local k;
           for k from 1+ `if`(n=1, -1, a(n-1))
           while not isprime(90*k+13) do od; k
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, Dec 06 2011
  • Mathematica
    Select[Range[0,4000],PrimeQ[90 #+13]&] (* Vincenzo Librandi, Dec 12 2011 *)
  • PARI
    is(n)=isprime(90*n+13) \\ Charles R Greathouse IV, Jul 12 2016

A201817 Numbers k such that 90*k + 67 is prime.

Original entry on oeis.org

0, 1, 3, 6, 8, 9, 10, 13, 14, 17, 19, 20, 23, 29, 30, 31, 33, 35, 36, 42, 44, 47, 50, 51, 56, 57, 61, 62, 63, 64, 66, 69, 70, 72, 73, 76, 77, 79, 83, 85, 90, 94, 96, 98, 100, 101, 103, 107, 108, 110, 117, 118, 120, 121, 122, 125, 127, 128, 129, 133, 138, 139
Offset: 1

Views

Author

J. W. Helkenberg, Dec 05 2011

Keywords

Comments

Looking at the format 90*k + 67 modulo 9 and modulo 10 we see that all entries of A142323 have digital root 4 and last digit 7. (Reverting the process is an application of the Chinese remainder theorem.)

Crossrefs

Programs

  • Magma
    [n: n in [0..200] | IsPrime(90*n+67)]; // Vincenzo Librandi, Dec 12 2011
    
  • Maple
    a:= proc(n) option remember; local k;
           for k from 1+ `if`(n=1, -1, a(n-1))
           while not isprime(90*k+67) do od; k
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, Dec 06 2011
  • Mathematica
    Select[Range[0,4000],PrimeQ[90 #+67]&] (* Vincenzo Librandi, Dec 12 2011 *)
  • PARI
    is(n)=isprime(90*n+67) \\ Charles R Greathouse IV, Feb 17 2017

A201820 Numbers k such that 90*k + 23 is prime.

Original entry on oeis.org

0, 1, 3, 4, 6, 7, 8, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 25, 28, 29, 32, 34, 39, 40, 42, 45, 47, 50, 52, 53, 55, 57, 59, 63, 64, 67, 68, 70, 76, 78, 84, 85, 87, 90, 95, 96, 97, 99, 102, 103, 105, 108, 109, 110, 112, 113, 116, 119, 122, 123, 125, 129, 131
Offset: 1

Views

Author

J. W. Helkenberg, Dec 05 2011

Keywords

Comments

This sequence was generated by adding 12 Fibonacci-like sequences. Looking at the format 90*k+23 modulo 9 and modulo 10 we see that all entries of A142324 have digital root 5 and last digit 3. (Reverting the process is an application of the Chinese remainder theorem.)

Crossrefs

Programs

Formula

a(n) = (A142324(n) - 23)/90.

A201822 Numbers k such that 90*k + 77 is prime.

Original entry on oeis.org

1, 2, 3, 6, 8, 9, 10, 15, 17, 18, 19, 20, 24, 26, 29, 30, 32, 34, 37, 40, 41, 43, 45, 46, 48, 54, 58, 59, 60, 62, 65, 68, 69, 74, 75, 76, 79, 82, 83, 85, 86, 87, 89, 93, 94, 95, 97, 102, 104, 109, 111, 113, 114, 115, 117, 122, 128, 130, 131, 135, 138, 144
Offset: 1

Views

Author

J. W. Helkenberg, Dec 05 2011

Keywords

Comments

Looking at the format 90k+77 modulo 9 and modulo 10 we see that all entries of A142329 have digital root 5 and last digit 7. (Reverting the process is an application of the Chinese remainder theorem.)

Crossrefs

Programs

Formula

a(n) = (A142329(n) - 77)/90.
Showing 1-10 of 21 results. Next