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.

A337489 a(n) is the k-th prime, such that abs(prime(k) - Sum_{j=k-1..k+1} prime(j)/3) sets a new record.

Original entry on oeis.org

3, 7, 29, 113, 523, 1151, 1327, 9551, 15683, 19609, 25471, 31397, 156007, 360653, 370261, 492113, 1349533, 1357201, 1357333, 1562051, 2010733, 4652507, 17051707, 17051887, 20831323, 47326693, 47326913, 122164747, 189695893, 191912783, 387096133, 428045741, 436273291
Offset: 1

Views

Author

Hugo Pfoertner, Aug 29 2020

Keywords

Comments

A337488 are the corresponding values of k.

Examples

			List of first terms:
   a(n) pi(a(n))  average-median
     3,      2,   1/3  = (2 + 3 + 5)/3 - 3
     7,      4,   2/3  = (5 + 7 + 11)/3 - 7
    29,     10,  -4/3  = (23 + 29 + 31)/3 - 29
   113,     30,  10/3
   523,     99,  16/3
  1151,    190, -20/3
  1327,    217,  28/3
  9551,   1183,  32/3
		

Crossrefs

Programs

  • PARI
    a337489(limp) = {my(p1=0, p2=2, p3=3, s=p1+p2+p3, d=0); forprime(p=5, limp, s=s-p1+p; my(dd=abs(s/3-p3)); if(dd>d, print1(p3, ", "); d=dd); p1=p2; p2=p3; p3=p)};
    a337489(500000000)

Extensions

Name edited by Peter Munn, Aug 01 2025

A337439 a(n) is the k-th prime, such that abs(prime(k) - Sum_{j=k-2..k+2} prime(j)/5) sets a new record.

Original entry on oeis.org

5, 7, 19, 47, 97, 109, 113, 199, 887, 1151, 1277, 1327, 9551, 11777, 14143, 15727, 19609, 25471, 31397, 156007, 360653, 370261, 492113, 1357201, 1357333, 1562051, 2010733, 4652507, 17051887, 20831323, 47326693, 47326913, 122164747, 189695893, 428045741, 436273291, 1453168433
Offset: 1

Views

Author

Hugo Pfoertner, Aug 29 2020

Keywords

Comments

A337438 are the corresponding values of k.

Examples

			List of first terms:
   a(n)  pi(a(n))  average-median
     5,      3,     3/5  = (2 + 3 + 5 + 7 + 11)/5 - 5
     7,      4,     4/5 = (3 + 5 + 7 + 11 + 13)/5 - 7
    19,      8,     6/5 = (13 + 17 + 19 + 23 + 29)/5 - 19
    47,     15,     8/5
    97,     25,   -12/5
   109,     29,    14/5
   113,     30,    22/5
   199,     46,    28/5
   887,    154,    34/5
  1151,    190,   -36/5
  1277,    206,   -38/5
  1327,    217,    12
  9551,   1183,    14
		

Crossrefs

Programs

  • PARI
    a337439(limp) = {my(p1=0,p2=2,p3=3,p4=5,p5=7,s=p1+p2+p3+p4+p5,d=0);forprime(p=11,limp, s=s-p1+p; my(dd=abs(s/5-p4)); if(dd>d,print1(p4,", ");d=dd); p1=p2;p2=p3;p3=p4;p4=p5;p5=p)};
    a337439(500000000)

Extensions

Name edited by Peter Munn, Aug 01 2025

A337488 a(n) is the index k of prime(k), such that abs(prime(k) - Sum_{j=k-1..k+1} prime(j)/3) sets a new record.

Original entry on oeis.org

2, 4, 10, 30, 99, 190, 217, 1183, 1831, 2225, 2810, 3385, 14358, 30802, 31545, 40933, 103520, 104071, 104072, 118506, 149689, 325853, 1094421, 1094422, 1319945, 2850174, 2850175, 6957876, 10539433, 10655462, 20684332, 22749705, 23163299, 33772762, 64955634, 64955635
Offset: 1

Views

Author

Hugo Pfoertner, Aug 29 2020

Keywords

Comments

A337489 are the corresponding primes.

Examples

			See A337489.
		

Crossrefs

Programs

  • PARI
    \\ See A337489, replace p3 by primepi(p3) in call of print1.

Extensions

Name edited by Peter Munn, Aug 01 2025
Showing 1-3 of 3 results.