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A217621 Primes of the form 2*n^2 + 90*n + 43. 9
43, 331, 2311, 3931, 7351, 8971, 18043, 19231, 23011, 31543, 33091, 37951, 46771, 50551, 58543, 60631, 81043, 133711, 149731, 173671, 188143, 226843, 251791, 296251, 310291, 319831, 364543, 385351, 395971, 412171, 417643, 439891, 474343, 540871, 625111, 631843 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: 2^a(n)-1 is not prime; in other words, these primes are included in A054723.

2*a(n) + 1939 is a square. - Vincenzo Librandi, Apr 09 2015

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..3000

MATHEMATICA

Select[Table[2 n^2 + 90 n + 43, {n, 0, 700}], PrimeQ]

PROG

(Magma) [a: n in [0..700] | IsPrime(a) where a is 2*n^2+90*n+43];

CROSSREFS

Cf. Primes of the form 2*n^2+2*(2*k+3)*n+(2*k+1): A176549 (k=0), A154577 (k=2), A154592 (k=3), A154601 (k=4), A217494 (k=7), A217495 (k=10), A217496 (k=11), A217497 (k=12), A217498 (k=13), A217499 (k=16), A217500 (k=17), A217501 (k=18), A217620 (k=19), this sequence (k=21).

Subsequence of A002145.

Sequence in context: A140012 A123795 A346575 * A213554 A164783 A291861

Adjacent sequences: A217618 A217619 A217620 * A217622 A217623 A217624

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Oct 09 2012

STATUS

approved

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Last modified March 28 12:50 EDT 2023. Contains 361585 sequences. (Running on oeis4.)