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 1-7 of 7 results.

A124485 Numbers n such that 2n-1 and 4n-1 are primes.

Original entry on oeis.org

2, 3, 6, 12, 15, 21, 27, 42, 45, 57, 66, 87, 90, 96, 117, 120, 126, 141, 147, 180, 210, 216, 222, 246, 255, 297, 321, 327, 330, 342, 360, 372, 381, 405, 456, 477, 507, 510, 516, 525, 552, 612, 615, 645, 705, 720, 726, 741, 750, 756, 780, 792, 801, 867, 906, 945
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Links

Crossrefs

Cf. A005384 (Sophie Germain primes).
Cf. A124486, A124487, A124488, A124489, A124490, A124491, A124492.

Programs

  • GAP
    Filtered([1..1000],p->IsPrime(2*p-1) and IsPrime(4*p-1)); # Muniru A Asiru, Jul 19 2018
  • Maple
    select(k->isprime(2*k-1) and isprime(4*k-1),[$1..1000]); # Muniru A Asiru, Jul 19 2018
  • Mathematica
    Select[Range[1000], And @@ PrimeQ /@ ({2, 4}*# - 1) &] (* Ray Chandler, Nov 21 2006 *)

Formula

a(n) = (A005384(n+1) + 1)/2. - Hilko Koning, Jul 19 2018

Extensions

Extended by Ray Chandler, Nov 21 2006

A124486 Numbers k such that 2*k-1, 4*k-1 and 6*k-1 are primes.

Original entry on oeis.org

2, 3, 12, 15, 42, 45, 87, 117, 120, 147, 210, 330, 477, 507, 612, 705, 780, 792, 945, 1002, 1065, 1170, 1275, 1347, 1470, 1680, 1695, 1797, 1902, 2175, 2187, 2205, 2460, 2472, 2667, 3057, 3087, 4047, 4137, 4257, 4530, 4740, 4770, 5082, 5157, 5295, 5775
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Links

Crossrefs

Cf. A124485-A124492.

Programs

  • Mathematica
    Select[Range[6000], And @@ PrimeQ /@ ({2, 4, 6}*# - 1) &] (* Ray Chandler, Nov 21 2006 *)

Extensions

Extended by Ray Chandler, Nov 21 2006

A124487 Numbers k such that 2*k-1, 4*k-1, 6*k-1 and 8*k-1 are primes.

Original entry on oeis.org

3, 45, 705, 945, 5295, 5775, 5955, 6450, 8580, 9945, 11175, 12120, 13095, 18000, 18525, 18690, 19710, 22440, 22785, 24960, 30390, 33780, 34335, 37665, 41790, 44460, 52185, 54180, 56175, 57300, 63570, 66990, 67515, 67725, 73335, 74700
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Links

Crossrefs

Cf. A124485-A124492.

Programs

  • Mathematica
    Select[Range[80000], And @@ PrimeQ /@ ({2, 4, 6, 8}*# - 1) &] (* Ray Chandler, Nov 21 2006 *)

Extensions

Extended by Ray Chandler, Nov 21 2006

A124488 Numbers k such that 2*k-1, 4*k-1, 6*k-1, 8*k-1 and 10*k-1 are primes.

Original entry on oeis.org

3, 45, 6450, 18000, 22785, 41790, 54180, 77385, 87675, 98385, 103005, 104520, 151515, 187005, 210210, 244590, 256620, 320775, 329175, 354795, 382875, 387975, 431385, 495540, 509355, 528510, 632775, 763815, 804870, 810540, 812175, 849285
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Links

Crossrefs

Cf. A124485-A124492.

Programs

  • Mathematica
    Select[Range[900000], And @@ PrimeQ /@ ({2, 4, 6, 8, 10}*# - 1) &] (* Ray Chandler, Nov 21 2006 *)

A124489 Numbers k such that 2*k-1, 4*k-1, 6*k-1, 8*k-1, 10*k-1 and 12*k-1 are primes.

Original entry on oeis.org

77385, 87675, 320775, 329175, 509355, 1137045, 1447110, 2623005, 3310965, 3974880, 4095000, 4339335, 5183220, 6163815, 6975780, 9080190, 9462285, 10957170, 11139975, 11148900, 12382755, 12796140, 15514695, 15917580
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Links

Crossrefs

Cf. A124485-A124492.

Programs

  • Mathematica
    Select[3*5*7*Range[160000], And @@ PrimeQ /@ ({2, 4, 6, 8, 10, 12}*# - 1) &] (* Ray Chandler, Nov 21 2006 *)
Select[Range[16*10^6],AllTrue[2*Range[6]#-1,PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Apr 19 2019 *)

A124491 Numbers n such that 2n-1, 4n-1, 6n-1, 8n-1, 10n-1, 12n-1, 14n-1 and 16n-1 are primes.

Original entry on oeis.org

1447110, 30020760, 32261985, 121012185, 203937090, 546020475, 546037695, 837344865, 1140530160, 2517567255, 2664703335, 2841691440, 2896212165, 3000108405, 3190108740, 5204790360, 5744351970, 6872932605, 7090912185
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Comments

All terms are multiples of 105. - Harvey P. Dale, May 08 2019

Crossrefs

Cf. A124485-A124492.

Programs

  • Mathematica
    k = 0;inc = 3*5*7;While[k < 7200000000,k += inc;While[Nand @@ PrimeQ /@ ({2, 4, 6, 8, 10, 12, 14, 16}*k - 1), k += inc];Print[k];];(* Ray Chandler, Nov 21 2006 *)
Select[Range[105,7091*10^6,105],AllTrue[2*Range[8]#-1,PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 08 2019 *)

Extensions

Corrected and extended by Ray Chandler, Nov 21 2006

A124490 Numbers n such that 2n-1, 4n-1, 6n-1, 8n-1, 10n-1, 12n-1 and 14n-1 are primes.

Original entry on oeis.org

1447110, 2623005, 4095000, 4339335, 6975780, 9080190, 12382755, 19455975, 20322960, 30020760, 32261985, 54202995, 62014155, 63196350, 66383520, 71369340, 94571295, 121012185, 124225920, 162780660, 177109380, 196068180, 223888665, 303047745, 310143960
Offset: 1

Views

Author

Artur Jasinski, Nov 04 2006

Keywords

Crossrefs

Cf. A124485-A124492.

Programs

  • Mathematica
    Select[3*5*7*Range[2000000], And @@ PrimeQ /@ ({2, 4, 6, 8, 10, 12, 14}*# - 1) &] (* Ray Chandler, Nov 21 2006 *)
pr7Q[n_]:=AllTrue[2*Range[7]n-1,PrimeQ]; Select[105*Range[3*10^6],pr7Q] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 17 2018 *)

Extensions

Extended by Ray Chandler, Nov 21 2006
More terms from Harvey P. Dale, May 17 2018
Showing 1-7 of 7 results.

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