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.

A089525 A089450 indexed by A000040.

Original entry on oeis.org

77, 87, 455, 3386, 7811, 11926, 12233, 12705, 13448, 15382, 16338, 17462, 17844, 18387, 18580, 20577, 22492, 25001, 26060, 32604, 34578, 42718, 52713, 55807, 60272, 65730, 67963, 77232, 85964, 92239, 98963, 99587, 100386, 102163, 103689
Offset: 1

Views

Author

Ray Chandler, Nov 07 2003

Keywords

Examples

			prime(44)=193, 2*193 + 3 = 389 = prime(77);
prime(45)=197, 2*197 + 3 = 397 = prime(78);
prime(46)=199, 2*199 + 3 = 401 = prime(79).
		

Crossrefs

Subsequence of A089529.

Formula

a(n) = k such that A089450(n) = A000040(k).
a(n) = A000720(A089450(n)). - Michel Marcus, Aug 04 2021

Extensions

Offset changed to 1 by Jinyuan Wang, Aug 04 2021

A088119 Sequence of primes p(n) such that 2*p(n)+3, 2*p(n+1)+3, 2*p(n+2)+3 are consecutive primes, where p(i) denotes the i-th prime.

Original entry on oeis.org

193, 223, 1607, 15733, 39877, 63647, 65407, 68207, 72673, 84299, 89977, 96787, 99137, 102533, 103687, 115837, 127807, 143567, 150373, 191999, 204793, 257867, 324217, 344957, 375253, 412033, 427433, 491149, 551717, 595117, 642527, 646897
Offset: 1

Views

Author

Pierre CAMI, Nov 02 2003

Keywords

Examples

			p(44) = 193, 2*193 + 3 = 389 = p(77);
p(45) = 197, 2*197 + 3 = 397 = p(78);
p(46) = 199, 2*199 + 3 = 401 = p(79).
		

Crossrefs

Subsequence of A089527.

Programs

  • Maple
    r:= 1: q:= 2: p:= 3: count:= 0:
    while count < 100 do
      r:= q; q:= p; p:= nextprime(p);
      if isprime(2*r+3) and nextprime(2*r+3)=2*q+3 and nextprime(2*q+3)=2*p+3 then
        count:= count+1;
        A[count]:= r;
      fi
    od:seq(A[i],i=1..100); # Robert Israel, Jul 01 2018

Formula

a(n) = A000040(A088066(n)).

Extensions

More terms from Ray Chandler, Nov 03 2003
Offset corrected by Robert Israel, Jul 01 2018

A088066 Numbers n such that 2*p(n)+3, 2*p(n+1)+3, 2*p(n+2)+3 are consecutive primes, where p(i) denotes the i-th prime.

Original entry on oeis.org

44, 48, 253, 1834, 4193, 6380, 6532, 6788, 7187, 8216, 8711, 9318, 9519, 9817, 9908, 10947, 11971, 13308, 13880, 17326, 18366, 22664, 27938, 29576, 31931, 34773, 35960, 40853, 45454, 48736, 52256, 52586, 53010, 53956, 54758, 59618, 62178
Offset: 1

Views

Author

Pierre CAMI, Nov 02 2003

Keywords

Examples

			p(44)=193, 2*193+3=389=p(77)
p(45)=197, 2*197+3=397=p(78)
p(46)=199, 2*199+3=401=p(79)
		

Crossrefs

Subsequence of A089526.

Extensions

More terms from Ray Chandler, Nov 03 2003

A089492 Sequence of primes 2*p(k) + 3 such that 2*p(k) + 3, 2*p(k+1) + 3, 2*p(k+2) + 3, 2*p(k+3) + 3 are consecutive primes, where p(i) denotes the i-th prime.

Original entry on oeis.org

1552237, 4315469, 8774137, 9629197, 10048081, 10875149, 11469389, 14498741, 18280861, 18789629, 19309957, 19309981, 25386029, 27265457, 28398641, 29697029, 31298269, 31355297, 36792901, 47318969, 47487889, 55449689
Offset: 1

Views

Author

Ray Chandler, Nov 04 2003

Keywords

Examples

			p(62178)=776117, 2*776117 + 3 = 1552237 = p(117814);
p(62179)=776119, 2*776119 + 3 = 1552241 = p(117815);
p(62180)=776137, 2*776137 + 3 = 1552277 = p(117816);
p(62181)=776143, 2*776143 + 3 = 1552289 = p(117817).
		

Crossrefs

Subsequence of A089450.

Programs

  • PARI
    a089492(limit)={my(pv=[2,3,5,0],v3=[3,3,3,3],ks(k)=2*k+3);forprime(p=7,limit,pv[4]=p;if(vecsum(isprime(2*pv+v3))==4&&primepi(ks(pv[4]))-primepi(ks(pv[1]))==3,print1(ks(pv[1]),", "));pv[1]=pv[2];pv[2]=pv[3];pv[3]=pv[4])};
    a089492(30000000) \\ Hugo Pfoertner, Aug 06 2021

Formula

a(n) = 2*A089007(n) + 3 = 2*A000040(A089009(n)) + 3 = A000040(A089524(n)).

Extensions

Offset changed to 1 by Jinyuan Wang, Aug 06 2021
Showing 1-4 of 4 results.