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 1-6 of 6 results.

A102326 Primes p such that the largest prime divisor of p^4+1 is less than p.

Original entry on oeis.org

10181, 14051, 18979, 25253, 57173, 58013, 60101, 62497, 65951, 66541, 69457, 75931, 82241, 82261, 84229, 87721, 88339, 88819, 91499, 92333, 95917, 99523, 105557, 107747, 109229, 118493, 118927, 137339, 146291, 155399, 157019
Offset: 1

Views

Author

Labos Elemer, Jan 05 2005

Keywords

Comments

Primes in A309562. - Robert Israel, Aug 09 2019

Examples

			p = 10181, 1+p^4 = 10743894862923122 = 2*17*1657*4657*5113*8009, so the largest prime factor is 8009 < p = 10181.
		

Crossrefs

Programs

  • Maple
    filter:= proc(p) max(numtheory:-factorset(p^4+1)) < p end proc:
    select(filter, [seq(ithprime(i),i=1..20000)]); # Robert Israel, Aug 09 2019
  • Mathematica
    <Ray Chandler, Jan 08 2005 *)
    Select[Prime[Range[15000]],FactorInteger[#^4+1][[-1,1]]<#&] (* Harvey P. Dale, Feb 27 2017 *)
  • PARI
    isok(p) = isprime(p) && (vecmax(factor(p^4+1)[,1]) < p); \\ Michel Marcus, Jul 09 2018

Extensions

Extended by Ray Chandler, Jan 08 2005

A091490 Primes p such that all prime divisors of p^2 + p + 1 are less than p.

Original entry on oeis.org

67, 79, 137, 149, 163, 181, 191, 211, 229, 263, 269, 277, 313, 373, 431, 439, 499, 521, 571, 631, 653, 787, 809, 811, 821, 823, 919, 947, 971, 991, 997, 1049, 1069, 1087, 1109, 1129, 1153, 1231, 1237, 1283, 1291, 1367, 1429, 1451, 1459, 1471, 1493, 1511
Offset: 1

Views

Author

R. K. Guy and Robert G. Wilson v, Jan 14 2004

Keywords

Crossrefs

Cf. A073501.

Programs

  • Mathematica
    PrimeFactors[ n_Integer ] := Flatten[ Table[ #[ [ 1 ] ], {1} ] & /@ FactorInteger[ n ] ]; Prime[ Select[ Range[ 242 ], Prime[ # ] > PrimeFactors[ Prime[ # ]^2 + Prime[ # ] + 1 ][ [ -1 ] ] & ] ]

A102325 Primes p such that the largest prime divisor of p^3 + 1 is less than p.

Original entry on oeis.org

17, 19, 23, 31, 101, 103, 173, 179, 257, 263, 293, 353, 373, 431, 467, 491, 521, 563, 593, 619, 641, 677, 719, 739, 773, 821, 829, 857, 859, 863, 881, 929, 941, 953, 1031, 1051, 1087, 1091, 1109, 1129, 1229, 1297, 1327, 1399, 1433, 1487, 1489, 1499, 1583
Offset: 1

Views

Author

Labos Elemer, Jan 05 2005

Keywords

Examples

			p = 17, 1 + p^3 = 1 + 4913 = 2*3*3*3*7*13, so the largest prime factor is 13 < p = 17.
		

Crossrefs

Programs

  • Mathematica
    <Ray Chandler, Jan 08 2005 *)

A102327 Primes p such that the largest prime factor of p^5 + 1 is less than p.

Original entry on oeis.org

1753, 2357, 7103, 9749, 13441, 16453, 21467, 22739, 25153, 28409, 29059, 33247, 33347, 36781, 42853, 51427, 57751, 58453, 62347, 65777, 66593, 69119, 72923, 78643, 80407, 83591, 85619, 89909, 91411, 99409, 101209, 101363, 113171, 124337
Offset: 1

Views

Author

Labos Elemer, Jan 05 2005

Keywords

Examples

			p = 1753, 1 + p^5 = 16554252702583994 = 2*41*151*691*877*1361*1621, so the largest prime factor is 1621 < p = 1753.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[15000]], Max[PrimeFactorList[1 + #^5]] < # &] (* Ray Chandler, Jan 08 2005 *)
    Select[Prime[Range[12000]],FactorInteger[#^5+1][[-1,1]]<#&]  (* Harvey P. Dale, Mar 14 2011 *)
  • PARI
    isok(p)= isprime(p) && (vecmax(factor(p^5+1)[,1]) < p); \\ Michel Marcus, Jul 11 2018

Formula

Solutions to {A006530(1 + p^5) < p} where p is a prime.

Extensions

Extended by Ray Chandler, Jan 08 2005

A102328 Primes p such that the largest prime divisor of p^6 + 1 is less than p.

Original entry on oeis.org

30977, 69127, 104681, 109807, 114671, 141637, 146057, 160319, 160639, 170371, 171169, 176087, 211723, 216119, 217081, 319321, 381673, 389083, 390151, 416219, 437401, 484609, 492257, 525571, 564713, 565241, 574127, 591601, 612173, 621259
Offset: 1

Views

Author

Labos Elemer, Jan 05 2005

Keywords

Examples

			p = 30977, p^6 + 1 = 883560179055825771003237890 = 2*5*13*37*61*113*181*13921*18517*22189*25741, so the largest prime factor is 25741 < p = 30977.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[60000]], Max[PrimeFactorList[1 + #^6]] < # &] (* Ray Chandler, Jan 08 2005 *)
  • PARI
    is(k) = isprime(k) && vecmax(factor(k^6+1)[, 1]) < k; \\ Amiram Eldar, Jun 21 2024

Formula

Solutions to {A006530(p^6+1) < p} where p is a prime number.

Extensions

Extended by Ray Chandler, Jan 08 2005

A102329 a(n) is the least prime p such that the largest prime divisor of 1+p^n is less than p.

Original entry on oeis.org

3, 7, 17, 10181, 1753, 30977, 1507853
Offset: 1

Views

Author

Labos Elemer, Jan 05 2005

Keywords

Comments

First term of sequences A065091, A073501, A102325-A102328.
These are the smallest p primes such that 1+p^n are p-smooth, i.e. with all prime-divisors less than p. The same holds for A102325-A102328. For the majority of p's, 1+p^n appear to be not p-smooth, i.e. have large enough greatest prime divisors.
a(8) > 4.5*10^6. - Giovanni Resta, May 02 2017

Crossrefs

Extensions

a(7)=1507853 from Ray Chandler, Jan 08 2005
Showing 1-6 of 6 results.