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.

A102339 Numbers k such that k*10^3 + 333 is prime.

Original entry on oeis.org

2, 5, 7, 10, 16, 17, 19, 20, 23, 29, 31, 38, 41, 49, 50, 55, 56, 59, 61, 64, 71, 76, 79, 85, 92, 100, 101, 103, 121, 134, 136, 139, 140, 143, 149, 154, 155, 161, 175, 176, 178, 182, 184, 188, 208, 209, 211, 217, 220, 232, 236, 239, 241, 244, 265, 266, 269, 271, 272, 274, 286, 287, 295, 299, 301, 308
Offset: 1

Views

Author

Parthasarathy Nambi, Feb 20 2005

Keywords

Comments

10^3 and 333 are relatively prime, therefore by Dirichlet's theorem there are infinitely many primes in the arithmetic progression n*10^3+333. No term of the sequence is of the form 3*k, because 3*k*10^3+333 = 3*(k*10^3+111) is divisible by 3, violating the requirement of the definition. - Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 27 2009

Examples

			If k=2,  then k*10^3 + 333 =  2333 (prime).
If k=49, then k*10^3 + 333 = 49333 (prime).
If k=92, then k*10^3 + 333 = 92333 (prime).
		

Crossrefs

Programs

  • Magma
    [ n: n in [1..700] | IsPrime(Seqint([3,3,3] cat Intseq(n))) ]; // Vincenzo Librandi, Feb 04 2011
    
  • Magma
    [ n: n in [0..320] | IsPrime(n*10^3+333) ]; // Klaus Brockhaus, May 20 2009
    
  • Mathematica
    Select[Range[400],PrimeQ[FromDigits[Join[IntegerDigits[#],{3,3,3}]]]&] (* Harvey P. Dale, Oct 14 2014 *)
    Select[Range[0, 1000], PrimeQ[1000 # + 333] &] (* Vincenzo Librandi, Jan 19 2013 *)
  • PARI
    is(n)=isprime(1000*n+333) \\ Charles R Greathouse IV, Jun 06 2017

A102340 Numbers k such that k3333 is prime.

Original entry on oeis.org

2, 10, 14, 31, 32, 34, 35, 49, 52, 73, 74, 79, 80, 92, 95, 97, 113, 116, 118, 125, 127, 128, 134, 136, 139, 142, 148, 149, 155, 160, 169, 172, 178, 185, 196, 205, 211, 217, 224, 227, 238, 245, 251, 260, 262, 263, 265, 272, 281, 283, 284, 287, 296, 298, 304, 305, 311, 322, 323, 325, 326, 335, 343
Offset: 1

Views

Author

Parthasarathy Nambi, Feb 20 2005

Keywords

Examples

			k=2 is in the sequence because  k3333 = 23333 is prime.
k=73 is in the sequence because k3333 = 733333 is prime.
k=125 is in the sequence because k3333 = 1253333 is prime.
		

Crossrefs

Cf. A101472.

Programs

  • Magma
    [ n: n in [1..700] | IsPrime(Seqint([3,3,3,3] cat Intseq(n))) ]; // Vincenzo Librandi, Feb 04 2011
  • Mathematica
    Select[Range[500],PrimeQ[FromDigits[Join[IntegerDigits[#],{3,3,3,3}]]]&] (* Harvey P. Dale, Jun 17 2014 *)
    Select[Range[500],PrimeQ[#*10^4+3333]&] (* Harvey P. Dale, Jun 15 2024 *)

A104130 Numbers n such that n33 is prime and n is a multiple of ten.

Original entry on oeis.org

10, 130, 140, 160, 170, 250, 290, 310, 340, 490, 500, 640, 650, 670, 910, 920, 940, 1040, 1060, 1070, 1180, 1190, 1220, 1270, 1280, 1330, 1340, 1360, 1390, 1460, 1490, 1600, 1610, 1670, 1790, 1910, 1960, 1970, 1990, 2000, 2050, 2060, 2140, 2170, 2240, 2440, 2450, 2480, 2510, 2560
Offset: 1

Views

Author

Parthasarathy Nambi, Mar 06 2005

Keywords

Examples

			If t=10, then t33 = 1033 (prime).
If t=170, then t33 = 17033 (prime).
If t=490, then t33 = 49033 (prime).
		

Crossrefs

Intersection of A008592 and A101472.

Programs

  • Mathematica
    Select[10 Range[300],PrimeQ[100#+33]&] (* Harvey P. Dale, Jan 08 2021 *)
  • PARI
    for(k=1,230,if(isprime(1000*k+33),print1(10*k,", "))) \\ Hugo Pfoertner, Dec 21 2019
Showing 1-3 of 3 results.