A247966 -id:A247966 - cp's OEIS frontend

A253915 Primes p such that the polynomial k^4 + k^3 + k^2 + k + p yields primes for k = 0..8, but not for k = 9.

43, 967, 11923, 213943, 2349313, 3316147, 30637567, 33421159, 39693817, 49978447, 105963769, 143405887, 148248949, 153756073, 156871549, 172981279, 187310803, 196726693, 203625283, 211977523, 220825453, 268375879, 350968543, 357834283, 414486697, 427990369

Offset: 1

K. D. Bajpai, Jan 18 2015

nonn

All the terms in this sequence are congruent to 1 (mod 3).

			a(1) = 43:
0^4 + 0^3 + 0^2 + 0 + 43 =   43;
1^4 + 1^3 + 1^2 + 1 + 43 =   47;
2^4 + 2^3 + 2^2 + 2 + 43 =   73;
3^4 + 3^3 + 3^2 + 3 + 43 =  163;
4^4 + 4^3 + 4^2 + 4 + 43 =  383;
5^4 + 5^3 + 5^2 + 5 + 43 =  823;
6^4 + 6^3 + 6^2 + 6 + 43 = 1597;
7^4 + 7^3 + 7^2 + 7 + 43 = 2843;
8^4 + 8^3 + 8^2 + 8 + 43 = 4723;
all nine are primes, and
9^4 + 9^3 + 9^2 + 9 + 43 = 7423 = 13*571 is composite.
The next prime for p=43 appears for k=13, namely 30983.

Jon E. Schoenfield, Table of n, a(n) for n = 1..155 (terms < 2*10^10)

Cf. A027445, A144051, A187057, A187058, A187060, A190800, A191456, A191457, A191458, A247949, A247966, A248206.

Select[Prime[Range[118*10^5]],AllTrue[#+{0,4,30,120,340,780,1554,2800,4680},PrimeQ]&&CompositeQ[#+7380]&] (* Harvey P. Dale, Sep 10 2021 *)

forprime(p=1, 1e10, if(isprime(p+4)&& isprime(p+30)&& isprime(p+120)&& isprime(p+340)&& isprime(p+780)&& isprime(p+1554)&& isprime(p+2800)&& isprime(p+4680) && !isprime(p+7380), print1(p,", ")))

Edited by Wolfdieter Lang, Feb 20 2015

Corrected and extended by Harvey P. Dale, Sep 10 2021

A347537 a(n) is the smallest prime p such that the polynomial k^4 + k^3 + k^2 + k + p yields primes for k = 0..n-1, but not for k = n.

Original entry on oeis.org

2, 3, 13, 37, 109, 7, 1093, 457, 43, 430879, 130901527, 1838420599, 48181700197

Offset: 1

Jon E. Schoenfield, Sep 11 2021

			At k=0, k^4 + k^3 + k^2 + k + p is, of course, prime for every prime p.
a(1)=2 because 2 is the smallest prime p such that 1^4 + 1^3 + 1^2 + 1 + p = 4 + p is not prime: 4 + 2 = 6 = 2*3.
a(2)=3 because 3 is the smallest prime p such that k^4 + k^3 + k^2 + k + p is prime for k=1 but not for k=2, i.e., such that 4 + p is prime but 2^4 + 2^3 + 2^2 + 2 + p = 30 + p is not prime: 4 + 3 = 7 is prime but 30 + 3 = 33 = 3*11.
a(6)=7 because 7 is the smallest prime p such that k^4 + k^3 + k^2 + k + p is prime for k = 1..5, but not for k = 6: 4 + 7 = 11, 30 + 7 = 37, 120 + 7 = 127, 340 + 7 = 347, and 780 + 7 = 787, but 1554 + 7 = 1561 = 7*223.

Cf. A247949, A247966, A248206, A253915.

a(13) from Jinyuan Wang, Sep 11 2021

cp's OEIS Frontend

A253915 Primes p such that the polynomial k^4 + k^3 + k^2 + k + p yields primes for k = 0..8, but not for k = 9.

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