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.

Previous Showing 11-17 of 17 results.

A289353 Primes p such that (p,p+4) is a pair of cousin primes and p == 7 (mod 10).

Original entry on oeis.org

7, 37, 67, 97, 127, 277, 307, 397, 457, 487, 757, 877, 907, 937, 967, 1087, 1297, 1447, 1567, 1597, 1867, 2137, 2347, 2377, 2437, 2617, 2707, 2797, 2857, 3037, 3187, 3217, 3457, 3697, 3847, 3877, 3907, 4447, 5077, 5167, 5227, 5347, 5437, 5527, 5647, 5737, 5857, 6007, 6217, 6547, 6577
Offset: 1

Views

Author

Muniru A Asiru, Jul 03 2017

Keywords

Comments

For cousin primes (p,p+4) such that p == 9 (mod 10), see A074822.
Members of A023200 with a last digit of 7. - Iain Fox, Dec 22 2017

Examples

			The pair of cousin prime (3,7) is not a member since 3 mod 10 = 3.
For p = 97, we get that (97,101) is a cousin prime pair and 97 == 7 (mod 10).
		

Crossrefs

Programs

  • GAP
    P:=Filtered([1..10000],IsPrime);;
    P1:=List(Filtered(Filtered(List([1..Length(P)-1],n->[P[n],P[n+1]]),i->i[2]-i[1]=4),j->j[1] mod 5 =2),k->k[1]);
    
  • Maple
    a:={}: for i from 1 to 1500 do if isprime(ithprime(i)+4) and ithprime(i) mod 10 = 7 then a:={op(a),ithprime(i)}: fi: od: a; # Muniru A Asiru, Aug 04 2017
  • Mathematica
    Select[10 Range[0, 660] + 7, PrimeQ[#] && PrimeQ[# + 4] &] (* Robert G. Wilson v, Dec 11 2017 *)
  • PARI
    isok(p) = isprime(p) && isprime(p+4) && ((p % 10) == 7); \\ Michel Marcus, Jul 03 2017
    
  • PARI
    is(n)=n%30==7 && isprime(n+4) && isprime(n) \\ Charles R Greathouse IV, Jul 13 2017

A119593 Primes for which the weight as defined in A117078 is 7 and the gap as defined in A001223 is 4.

Original entry on oeis.org

67, 193, 277, 487, 613, 823, 907, 1663, 1873, 2083, 2293, 2377, 2797, 3217, 3343, 3847, 4813, 5233, 5527, 5653, 5737, 6577, 6997, 7207, 7753, 8677, 8803, 9433, 11113, 11617
Offset: 1

Views

Author

Rémi Eismann, Jun 01 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (14i-3) with i=(level(n)+1)/2, level(n) defined in A117563.

Crossrefs

Programs

  • PARI
    forprimestep(p=67,1e4,14, t=p%5; if((t==2 || t==3) && isprime(p+4), print1(p", "))) \\ Charles R Greathouse IV, Sep 17 2022
    
  • PARI
    p=67; forprime(q=p+2,1e4, if(q-p==4 && (p%70==53 || p%70==67), print1(p", ")); p=q) \\ Charles R Greathouse IV, Sep 17 2022

Formula

Primes p such that (1) p = 53 or 67 mod 70 and (2) p+4 is prime. - Charles R Greathouse IV, Sep 17 2022
a(n) = Omega(n log^2 n). - Charles R Greathouse IV, Sep 17 2022

A119594 Primes for which the weight as defined in A117078 is 9 and the gap as defined in A001223 is 4.

Original entry on oeis.org

13, 103, 463, 643, 877, 967, 1093, 1597, 1867, 1993, 2137, 2857, 3037, 3163, 3253, 3613, 3793, 4153, 4513, 4783, 5413, 5503, 5647, 6007, 6043, 6547, 6907, 7537, 7573, 7933, 8167, 8293, 9157, 9337, 9463, 9787
Offset: 1

Views

Author

Rémi Eismann, Jun 01 2006, May 04 2007

Keywords

Comments

The prime numbers in this sequence are of the form (18i-5) with i=(level(n)+1)/2, level(n) defined in A117563.

Examples

			a(1)=13 because of 17=13+mod(13;9) and 17-13=4.
18*1-5=13, level=1
a(2)=103 because of 107=103+mod(103;9) and 107-103=4
18*((11+1)/2)-5=103, level=11
		

Crossrefs

A132255 Isolated primes congruent to {17, 19} mod 30.

Original entry on oeis.org

47, 79, 167, 257, 317, 379, 409, 439, 467, 499, 557, 587, 647, 677, 709, 739, 769, 797, 887, 919, 947, 977, 1009, 1039, 1069, 1097, 1129, 1187, 1217, 1249, 1307, 1367, 1399, 1459, 1549, 1579, 1637, 1759, 1847, 1907, 2179, 2207, 2297
Offset: 1

Views

Author

Omar E. Pol, Aug 20 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[500]],NoneTrue[#+{2,-2},PrimeQ]&&MemberQ[{17,19},Mod[#,30]]&]

A289413 Primes p such that (p,p+4) is a pair of cousin primes and p == 3 (mod 10).

Original entry on oeis.org

3, 13, 43, 103, 163, 193, 223, 313, 463, 613, 643, 673, 823, 853, 883, 1093, 1213, 1303, 1423, 1483, 1663, 1693, 1783, 1873, 1993, 2083, 2203, 2293, 2473, 2683, 2833, 2953, 3163, 3253, 3343, 3463, 3613, 3673, 3793, 3943, 4003, 4153, 4513, 4783, 4813, 4933, 5233, 5413, 5503, 5653, 5923
Offset: 1

Views

Author

Muniru A Asiru, Jul 06 2017

Keywords

Comments

For pairs of cousin primes (p,p+4) such that p == 9 (mod 10) and pairs of cousin primes (p,p+4) such that p == 7 (mod 10), see A074822 and A289353, respectively. A074822, A289353 and this sequence give all the lesser members p of pairs of cousin primes.

Examples

			For p = 193, the pair of cousin primes is (193, 197) and 193 == 3 (mod 10).
Although, the primes 3 and 7 are not consecutive primes, p = 3 yields the pair of cousin primes (3, 7) and 3 == 3 (mod 10).
		

Crossrefs

Programs

  • GAP
    P:=Filtered([1..10000],IsPrime);;
    P1:=Concatenation([3],List(Filtered(Filtered(List([1..Length(P)-1],n->[P[n],P[n+1]]),i->i[2]-i[1]=4),j->j[1] mod 10 = 3),k->k[1]));
    
  • Maple
    A289413:={}:  for i from 1 to 1500 do if isprime(ithprime(i) + 4) and ithprime(i) mod 10 = 3 then A289413:={op(A289413), ithprime(i)}: fi: od: A289413;
    # Alternative:
    select(t -> isprime(t) and isprime(t+4), [seq(i,i=3..10000, 10)]); # Robert Israel, Aug 02 2017
  • Mathematica
    Select[Prime[Range[800]],Mod[#,10]==3&&PrimeQ[#+4]&] (* Harvey P. Dale, Aug 22 2019 *)
  • PARI
    isok(p) = isprime(p) && isprime(p+4) && (p%10==3); \\ Michel Marcus, Jul 19 2017
    
  • PARI
    list(lim)=my(v=List([3]),p=13); forprime(q=17,lim+4, if(q-p==4 && p%10==3, listput(v,p)); p=q); Vec(v) \\ Charles R Greathouse IV, Aug 03 2017

A132252 Isolated primes congruent to 19 (mod 30).

Original entry on oeis.org

79, 379, 409, 439, 499, 709, 739, 769, 919, 1009, 1039, 1069, 1129, 1249, 1399, 1459, 1549, 1579, 1759, 2179, 2389, 2539, 2719, 2749, 3019, 3049, 3079, 3109, 3229, 3319, 3499, 3709, 3739, 3889, 4099, 4729, 4759, 4909, 4999, 5059, 5119
Offset: 1

Views

Author

Omar E. Pol, Aug 20 2007

Keywords

Crossrefs

A132257 Isolated primes congruent to {11, 13, 17, 19} mod 30.

Original entry on oeis.org

47, 79, 131, 163, 167, 223, 251, 257, 317, 373, 379, 401, 409, 439, 467, 491, 499, 557, 587, 613, 647, 673, 677, 701, 709, 733, 739, 761, 769, 797, 853, 887, 911, 919, 941, 947, 971, 977, 1009, 1039, 1069, 1097, 1123, 1129, 1181, 1187
Offset: 1

Views

Author

Omar E. Pol, Aug 20 2007

Keywords

Crossrefs

Previous Showing 11-17 of 17 results.