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 12 results. Next

A154486 a(n+1)-+a(n)=prime, a(1)=0,a(2)=5.

Original entry on oeis.org

0, 5, 8, 11, 18, 23, 30, 37, 42, 47, 50, 53, 56, 75, 82, 85, 88, 91, 102, 109, 114, 119, 122, 129, 134, 137, 140, 143, 150, 157, 160, 171, 176, 183, 190, 193, 196, 201, 208, 211, 222, 227, 230, 233, 246, 253, 256, 267, 274, 297, 302, 305, 308, 311, 330, 343, 348
Offset: 1

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Author

Keywords

Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers : 8-5=3;8+5=13, 11-8=3;11+8=19, 18-11=7;18+11=29,...

Crossrefs

Essentially the same as A154484 and A154485.

Programs

  • Mathematica
    a=0;b=5;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b],AppendTo[lst,n];a=b;b=n],{n,b+1,7!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154487 a(n+1)-+a(n)=prime, a(1)=0,a(2)=7.

Original entry on oeis.org

0, 7, 10, 13, 16, 21, 26, 33, 38, 41, 48, 53, 56, 75, 82, 85, 88, 91, 102, 109, 114, 119, 122, 129, 134, 137, 140, 143, 150, 157, 160, 171, 176, 183, 190, 193, 196, 201, 208, 211, 222, 227, 230, 233, 246, 253, 256, 267, 274, 297, 302, 305, 308, 311, 330, 343
Offset: 1

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Author

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Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers : 10-7=3;10+7=17, 230-227=3;230+227=457, 233-230=3;233+230=463,...
Essentially the same as A090955. - R. J. Mathar, Jan 12 2009

Crossrefs

Programs

  • Mathematica
    a=0;b=7;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b],AppendTo[lst,n];a=b;b=n],{n,b+1,7!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154488 a(n+1)-+a(n)=prime, a(1)=1,a(2)=12.

Original entry on oeis.org

1, 12, 17, 20, 23, 30, 37, 42, 47, 50, 53, 56, 75, 82, 85, 88, 91, 102, 109, 114, 119, 122, 129, 134, 137, 140, 143, 150, 157, 160, 171, 176, 183, 190, 193, 196, 201, 208, 211, 222, 227, 230, 233, 246, 253, 256, 267, 274, 297, 302, 305, 308, 311, 330, 343, 348
Offset: 1

Views

Author

Keywords

Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers : 230-227=3;230+227=457, 233-230=3;233+230=463,...

Crossrefs

Programs

  • Mathematica
    a=1;b=12;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b],AppendTo[lst,n];a=b;b=n],{n,b+1,7!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154493 a(n+1)-+a(n)=prime, a(n+1)*a(n)=Average of twin prime pairs, a(1)=1,a(2)=4.

Original entry on oeis.org

1, 4, 15, 28, 39, 50, 81, 350, 459, 512, 675, 944, 987, 1040, 1917, 1936, 2325, 2378, 2421, 2588, 2745, 2812, 3459, 3488, 3495, 3506, 5667, 5804, 6027, 6074, 24765, 24832, 25479, 25552, 27621, 27848, 27951, 27980, 34101, 34720, 34773, 35344
Offset: 1

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Author

Keywords

Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers and multiplication and any two consecutive numbers is Average of twin prime pairs : 4-1=3;4+1=5;4*1=4, 15-4=11;15+4=19;15*4=60, ...

Crossrefs

Programs

  • Mathematica
    a=1;b=4;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b]&&PrimeQ[n*b-1]&&PrimeQ[n*b+1],AppendTo[lst,n];a=b;b=n],{n,b+1,9!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154494 a(n+1) -+ a(n) = prime, a(n+1)*a(n) = average of twin prime pairs, a(1)=1, a(2)=6.

Original entry on oeis.org

1, 6, 17, 84, 247, 300, 341, 720, 767, 834, 913, 960, 989, 1590, 1741, 2772, 2945, 3102, 3451, 3540, 3563, 4020, 4159, 4812, 5431, 5700, 6131, 6192, 6245, 8586, 9373, 10056, 10163, 10314, 10543, 10944, 11033, 11844, 12055, 13566, 14015, 15048, 15155
Offset: 1

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Author

Keywords

Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers and multiplication and any two consecutive numbers is Average of twin prime pairs : 6-1=5; 6+1=7; 6*1=6, 17-6=11; 17+6=23; 17*6=102, ... .

Crossrefs

Programs

  • Maple
    f:= proc(x) local k;
      for k from x+1 by 2 do
        if isprime(k+x) and isprime(k-x) and isprime(k*x-1) and isprime(k*x+1) then return k fi
      od;
    end proc:
    R:= 1,6: x:= 6:
    for count from 3 to 100 do
      x:= f(x);
      R:= R,x
    od:
    R; # Robert Israel, Nov 29 2023
  • Mathematica
    a=1;b=6;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b]&&PrimeQ[n*b-1]&&PrimeQ[n*b+1],AppendTo[lst,n];a=b;b=n],{n,b+1,9!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154495 a(n+1)-+a(n)=prime, a(n+1)*a(n)=Average of twin prime pairs, a(1)=2,a(2)=9.

Original entry on oeis.org

2, 9, 20, 33, 40, 141, 298, 435, 536, 687, 884, 1197, 1244, 1665, 1792, 2235, 2486, 2595, 2602, 3765, 3784, 4095, 4148, 4605, 4868, 5061, 5330, 6159, 6220, 6579, 6662, 7119, 7162, 7341, 8288, 10791, 11438, 11859, 12142, 12825, 13274, 14553, 14734
Offset: 1

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Author

Keywords

Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers and multiplication and any two consecutive numbers is Average of twin prime pairs : 9-2=7;9+2=11;9*2=18, ...

Crossrefs

Programs

  • Maple
    A:= 2,9: b:= 9:
    for i from 3 to 100 do
      p:= 2:
      do
        p:= nextprime(p);
        k:= b + p;
        if isprime(b*k+1) and isprime(b*k-1) and isprime(k+b) then
           A:= A,k; b:= k; break
    fi od od:
    A; # Robert Israel, Jan 01 2024
  • Mathematica
    a=2;b=9;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b]&&PrimeQ[n*b-1]&&PrimeQ[n*b+1],AppendTo[lst,n];a=b;b=n],{n,b+1,9!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154496 a(n+1)-+a(n)=prime, a(n+1)*a(n)=Average of twin prime pairs, a(1)=3,a(2)=10.

Original entry on oeis.org

3, 10, 27, 74, 3093, 3104, 3417, 3580, 3597, 3614, 5907, 5960, 6651, 6962, 9045, 9098, 10479, 10708, 13299, 13382, 14055, 14438, 15099, 16082, 16101, 16112, 16521, 16982, 17505, 19328, 19605, 20062, 22131, 22840, 23013, 23036, 23265, 23422
Offset: 1

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Author

Keywords

Comments

Sum and difference of any of two consecutive numbers in current sequence are prime numbers and multiplication and any two consecutive numbers is Average of twin prime pairs : 10-3=7;10+3=13;10*3=30, ...

Crossrefs

Programs

  • Mathematica
    a=3;b=10;lst={a,b};Do[If[PrimeQ[n-b]&&PrimeQ[n+b]&&PrimeQ[n*b-1]&&PrimeQ[n*b+1],AppendTo[lst,n];a=b;b=n],{n,b+1,9!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154497 a(n) is the least prime > a(n-1) such that a(n-2) + a(n-1) + a(n) is prime, with a(1)=3, a(2)=11.

Original entry on oeis.org

3, 11, 17, 19, 23, 29, 31, 37, 41, 53, 73, 97, 101, 109, 127, 131, 139, 149, 151, 157, 179, 211, 223, 227, 233, 241, 269, 277, 281, 349, 353, 359, 379, 433, 467, 499, 521, 523, 557, 577, 587, 613, 631, 743, 757, 769, 821, 827, 829, 883, 947, 967, 983, 1013, 1087
Offset: 1

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Keywords

Examples

			3+11+17 = 31, 11+17+19 = 47, 17+19+23 = 59, ...
		

Crossrefs

Programs

  • Maple
    A[1]:= 3: A[2]:= 11:
    for i from 3 to 100 do
      p:= A[i-1];
      do
        p:= nextprime(p);
        if isprime(A[i-2]+A[i-1]+p) then
           A[i]:= p; break
        fi
      od
    od:
    seq(A[i],i=1..100); # Robert Israel, Jan 17 2023
  • Mathematica
    a=3;b=11;lst={a,b};Do[c=Prime[n];p=a+b+c;If[PrimeQ[p],AppendTo[lst,c];a=b;b=c],{n,5,6!}];lst

Extensions

NAME adapted to offset by R. J. Mathar, Jun 19 2021
Name corrected by Robert Israel, Jan 17 2023

A154498 Sum of any 3 consecutive numbers is prime, a(1)=41,a(2)=43.

Original entry on oeis.org

41, 43, 47, 59, 61, 71, 79, 83, 89, 97, 107, 109, 131, 139, 149, 151, 157, 179, 211, 223, 227, 233, 241, 269, 277, 281, 349, 353, 359, 379, 433, 467, 499, 521, 523, 557, 577, 587, 613, 631, 743, 757, 769, 821, 827, 829, 883, 947, 967, 983, 1013, 1087, 1091
Offset: 1

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Author

Keywords

Comments

41+43+47=171,...

Crossrefs

Programs

  • Mathematica
    a=41;b=43;lst={a,b};Do[c=Prime[n];p=a+b+c;If[PrimeQ[p],AppendTo[lst,c];a=b;b=c],{n,15,5!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021

A154500 Sum of any 3 consecutive numbers is prime and |a(n+2) - (a(n+1) + a(n))| is prime, a(1)=3, a(2)=5.

Original entry on oeis.org

3, 5, 11, 13, 17, 23, 27, 33, 37, 39, 63, 65, 69, 93, 95, 105, 111, 115, 123, 129, 145, 147, 165, 175, 183, 219, 229, 285, 315, 319, 357, 363, 367, 393, 411, 425, 447, 489, 493, 549, 555, 563, 615, 669, 713, 729, 765, 775, 801, 807, 839, 885, 897, 901, 915, 933, 941, 945, 957, 995, 1005, 1023, 1051
Offset: 1

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Author

Keywords

Examples

			3+5+11=19; 11-(3+5)=3, 5+11+13=29; 13-(5+11)=-3, 11+13+17=41; 17-(11+13)=-7, 13+17+23=53; 23-(13+17)=-7,... .
		

Crossrefs

Programs

  • Maple
    R:= 3,5: count:= 2:
    a:= 3: b:= 5:
    for x from b+2 by 2 while count < 100 do
       if isprime(a+b+x) and isprime(abs(x-(a+b))) then
         R:= R, x; a:= b; b:= x; count:= count+1;
       fi
    od:
    R; # Robert Israel, Nov 29 2023
  • Mathematica
    a=3;b=5;lst={a,b};Do[c=Prime[n];p1=c+a+b;p2=c-(a+b);If[PrimeQ[p1]&&PrimeQ[p2],AppendTo[lst,c];a=b;b=c],{n,5,9!}];lst

Extensions

NAME adapted to offset. - R. J. Mathar, Jun 19 2021
Corrected and extended by Robert Israel, Nov 29 2023
Showing 1-10 of 12 results. Next