A171058
Numbers k such that 3^k + 3*k + 1 is prime.
Original entry on oeis.org
0, 1, 3, 41, 45, 83, 95, 181, 193, 195, 311, 325, 901, 1825, 3649, 7709, 16335, 45547
Offset: 1
Numbers k such that b^k + b*k + 1 is prime:
A301634 (b=2), this sequence (b=3),
A301635 (b=5).
A301634
Numbers k such that 2^k + 2*k + 1 is prime.
Original entry on oeis.org
0, 1, 5, 13, 65, 85, 229, 2005, 3875, 3919, 5417, 8819, 11899, 16668, 19445, 28242, 33407, 37918, 40594, 141251
Offset: 1
Numbers k such that b^k + b*k + 1 is prime: this sequence (b=2),
A171058 (b=3),
A301635 (b=5).
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a:=k->`if`(isprime(2^k+2*k+1),k,NULL): seq(a(k),k=0..6000); # Muniru A Asiru, Mar 25 2018
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Flatten[{0, Select[Range[5000], PrimeQ[2^# + 2*# + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *)
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for(n=0, 500, if(isprime(2^n+2*n+1), print1(n", ")))
A301638
Primes of the form 5^k + 5*k + 1.
Original entry on oeis.org
2, 11, 48828181, 298023223876953251, 2910383045673370361328301, 258493941422821148397315216271863391739316284656524658203551
Offset: 1
Primes of the form b^k+b*k+1:
A163115 (b=2),
A180269 (b=3), this sequence (b=5).
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Select[Table[5^n+5n+1,{n,0,550}],PrimeQ] (* Harvey P. Dale, Dec 03 2018 *)
Showing 1-3 of 3 results.
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