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.

A053183 Primes of the form p^2 + p + 1 when p is prime.

Original entry on oeis.org

7, 13, 31, 307, 1723, 3541, 5113, 8011, 10303, 17293, 28057, 30103, 86143, 147073, 459007, 492103, 552793, 579883, 598303, 684757, 704761, 735307, 830833, 1191373, 1204507, 1353733, 1395943, 1424443, 1482307, 1886503, 2037757
Offset: 1

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Author

Enoch Haga, Mar 01 2000

Keywords

Comments

Also primes in A001001. - Philippe Deléham, Feb 21 2004
This sequence is a subsequence of A002383. These numbers are repunit primes 111_n, so they are Brazilian primes belonging to A085104. - Bernard Schott, Dec 21 2012
Also, primes in A060800. - Zak Seidov, Mar 21 2014
Also subsequence of A002061, A193574. - Hartmut F. W. Hoft, May 05 2017
As p^2 + p + 1 is the sum of divisors of p^2 for any prime p, this is a subsequence of A023195. - Peter Munn, Feb 16 2018

Crossrefs

Programs

  • Mathematica
    a053183[n_] := Select[Map[Prime[#]^2 + Prime[#] + 1&, Range[n]], PrimeQ]
    a053183[225] (* data *) (* Hartmut F. W. Hoft, May 05 2017 *)
    Select[Table[p^2+p+1,{p,Prime[Range[300]]}],PrimeQ] (* Harvey P. Dale, Aug 15 2017 *)

Formula

a(n) = A053182(n)^2 + A053182(n) + 1.

A190527 Primes of the form p^4 + p^3 + p^2 + p + 1, where p is prime.

Original entry on oeis.org

31, 2801, 30941, 88741, 292561, 732541, 3500201, 28792661, 39449441, 48037081, 262209281, 1394714501, 2666986681, 3276517921, 4802611441, 5908670381, 12936304421, 16656709681, 19408913261, 24903325661, 37226181521, 43713558101, 52753304641, 64141071121, 96427561501, 100648118041
Offset: 1

Views

Author

Bernard Schott, Dec 20 2012

Keywords

Comments

These primes are generated by exactly A065509, cf. 2nd formula.
These numbers are repunit primes 11111_p, so they are Brazilian primes (A085104).
When p^4 + p^3 + p^2 + p + 1 = sigma(p^4) is prime, then it equals A193574(p^4), so that this sequence is a subsequence of A193574; by definition it is also a subsequence of A053699 and A131992. - Hartmut F. W. Hoft, May 05 2017

Examples

			a(3) = 30941 = 11111_13 = 13^4 + 13^3 + 13^2 + 13^1 + 1 is prime.
		

Crossrefs

Cf. A049409 (n^4 + ... + 1 is prime), A065509 (primes among these n), A193574.
Subsequence of A088548 (primes n^4 + ... + 1) and A085104 ("Brazilian" primes, of the form 1 + n + n^2 + ... + n^k).
Intersection of A000040 (primes) and A131992 (p^4 + ... + 1), subsequence of A053699 (n^4 + ... + 1).

Programs

  • Magma
    [p: p in PrimesUpTo(600) | IsPrime(p) where p is p^4 +p^3+p^2+p+1]; // Vincenzo Librandi, May 06 2017
    
  • Mathematica
    a190527[n_] := Select[Map[(Prime[#]^5-1)/(Prime[#]-1)&, Range[n]], PrimeQ]
    a190527[100] (* data *) (* Hartmut F. W. Hoft, May 05 2017 *)
    Select[#^4 + #^3 + #^2 + # + 1 &/@Prime[Range[100]], PrimeQ] (* Vincenzo Librandi, May 06 2017 *)
  • PARI
    [q|p<-primes(100),ispseudoprime(q=(p^5-1)\(p-1))]
    A190527_vec(N)=[(p^5-1)\(p-1)|p<-A065509_vec(N)] \\ M. F. Hasler, Mar 03 2020

Formula

a(n) = A193574(A065509(n)^4). - Hartmut F. W. Hoft, May 08 2017
a(n) = A053699(A065509(n)) = A000203(A065509(n)^4). - M. F. Hasler, Mar 03 2020

Extensions

a(7) corrected and a(18)-a(26) added by Hartmut F. W. Hoft, May 05 2017
Edited by M. F. Hasler, Mar 06 2020

A194257 Primes of the form p^6 + p^5 + p^4 + p^3 + p^2 + p + 1 when p is prime.

Original entry on oeis.org

127, 1093, 19531, 5229043, 25646167, 917087137, 52379047267, 153436090543, 502628805631, 11016462577051, 18871143464293, 251059142817757, 1812169199976451, 1940350890330343
Offset: 1

Views

Author

Bernard Schott, Dec 21 2012

Keywords

Comments

These primes are generated by exactly A163268.
This sequence is included in A088550.
These numbers are repunit primes 1111111_n, so they are Brazilian primes and are terms of A085104.
Subsequence of A088550. - Hartmut F. W. Hoft, May 05 2017

Crossrefs

Programs

  • Maple
    select(isprime, map(p -> add(p^i,i=0..6), select(isprime, [2,seq(i,i=3..1000,2)]))); # Robert Israel, May 05 2017
  • Mathematica
    a194257[n_] := Select[Map[(Prime[#]^7-1)/(Prime[#]-1)&, Range[n]], PrimeQ]
    a194257[70] (* data *) (* Hartmut F. W. Hoft, May 05 2017 *)
    Select[Table[Total[p^Range[0,6]],{p,Prime[Range[100]]}],PrimeQ] (* Harvey P. Dale, Mar 09 2024 *)

Formula

a(n) = A193574(A163268(n)^6). - Hartmut F. W. Hoft, May 08 2017

A286301 Primes of the form p^10 + p^9 + p^8 + p^7 + p^6 + p^5 + p^4 + p^3 + p^2 + p + 1 when p is prime.

Original entry on oeis.org

12207031, 2141993519227, 178250690949465223, 2346320474383711003267, 398341412240537151131351, 79545183674814239059370551, 494424256962371823779424877, 8271964541879648991904246901, 32142180034067960734115528951, 91264002187709396686868598317
Offset: 1

Views

Author

Hartmut F. W. Hoft, May 05 2017

Keywords

Examples

			Prime number 12207031 = Sum_{i=0..10} 5^i is the first in the sequence since 23 divides 88573 = Sum_{i=0..10} 3^i as well as 2047 = Sum_{i=0..10} 2^i.
		

Crossrefs

Subsequence of A060885, A162861 and A193574.

Programs

  • Mathematica
    a286301[n_] := Select[Map[(Prime[#]^11-1)/(Prime[#]-1)&, Range[n]], PrimeQ]
    a286301[150] (* data *)
Showing 1-4 of 4 results.