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 1-4 of 4 results.

A072803 a(n) is n written in base n mod 10, or 0 if n mod 10 = 0.

Original entry on oeis.org

1, 10, 10, 10, 10, 10, 10, 10, 10, 0, 11111111111, 1100, 111, 32, 30, 24, 23, 22, 21, 0, 111111111111111111111, 10110, 212, 120, 100, 42, 36, 34, 32, 0, 1111111111111111111111111111111, 100000, 1020, 202, 120, 100, 52, 46, 43, 0
Offset: 1

Views

Author

Labos Elemer, Jul 12 2002

Keywords

Examples

			In base 1, n =11...11=n written n times; in base 0 baseform is taken as 0.

Crossrefs

Cf. A008713, A072804-A072807.

Programs

  • Mathematica
    Table[BaseForm[w, Mod[w, 10]], {w, 1, 128}]

A072805 Primes of form 4k+3 written in base 3.

Original entry on oeis.org

10, 21, 102, 201, 212, 1011, 1121, 1202, 2012, 2111, 2122, 2221, 10002, 10211, 10222, 11201, 11212, 12011, 12121, 20001, 20012, 20122, 21002, 21101, 21211, 22021, 22102, 22212, 100022, 100202, 101001, 101111, 102101, 102112, 110021
Offset: 1

Views

Author

Labos Elemer, Jul 12 2002

Keywords

Examples

			83 ~ 10002 in base 3.

Crossrefs

Cf. A008713, A072803-A072807.

Programs

  • Mathematica
    Do[s=Prime[n]; If[Mod[s, 4]==3, Print[BaseForm[s, 3]]], {n, 1, 256}]

A072804 n-th prime prime(n) written in base (prime(n) (mod 4)).

Original entry on oeis.org

10, 10, 11111, 21, 102, 1111111111111, 11111111111111111, 201, 212, 11111111111111111111111111111, 1011, 1111111111111111111111111111111111111, 11111111111111111111111111111111111111111, 1121, 1202, 11111111111111111111111111111111111111111111111111111, 2012
Offset: 1

Views

Author

Labos Elemer, Jul 12 2002

Keywords

Examples

			4k+1 primes are written in base 1, while 4k+3 primes are in base 3.

Links

Crossrefs

Cf. A008713, A072803, A072805, A072806, A072807.

Programs

  • Mathematica
    Table[FromDigits@ If[#2 == 1, ConstantArray[1, #1], IntegerDigits[#1, #2]] & @@ {#, Mod[#, 4]} &@ Prime@ w, {w, 17}] (* Michael De Vlieger, Sep 04 2019 *)
  • PARI
    a(n) = {my(p=prime(n)); if ((p % 4) != 1, fromdigits(digits(p, p % 4), 10), fromdigits(vector(p, k, 1), 10));} \\ Michel Marcus, Sep 04 2019

A072806 Primes of the form 6k+5 written in base 5.

Original entry on oeis.org

10, 21, 32, 43, 104, 131, 142, 203, 214, 241, 313, 324, 401, 412, 423, 1011, 1022, 1044, 1132, 1143, 1204, 1231, 1242, 1402, 1413, 1424, 2001, 2012, 2023, 2034, 2111, 2133, 2221, 2232, 2342, 2403, 2414, 3013, 3024, 3101, 3134, 3211, 3233, 3244, 3321
Offset: 1

Views

Author

Labos Elemer, Jul 12 2002

Keywords

Examples

			41 = 25 + 3*5 + 1 = 131_5.

Links

Crossrefs

Cf. A007091, A007528.
Cf. A008713, A072803, A072804, A072805, A072807.

Programs

  • Mathematica
    Do[s=Prime[n]; If[Mod[s, 6]==5, Print[BaseForm[s, 5]]], {n, 1, 256}]
FromDigits[IntegerDigits[#, 5]] & /@  Select[Table[6 n + 5, {n, 0, 100}], PrimeQ] (* Harvey P. Dale, Oct 05 2023 *)
  • PARI
    lista(nn) = for (n=0, nn, if (isprime(p=6*n+5), print1(fromdigits(digits(p, 5)), ", "))); \\ Michel Marcus, Jul 09 2018

Formula

a(n) = A007091(A007528(n)). - Michel Marcus, Jul 09 2018
Showing 1-4 of 4 results.

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

Content is available under The OEIS End-User License Agreement.