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A281295 Primes which cannot be written as x^2 + 11*y^2, where x, y > 0. 0
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 167, 173, 179, 181, 191, 193, 197, 211, 223, 227, 229, 233, 239, 241, 251, 263, 271, 277, 281, 283, 293, 307, 313, 317 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Integers n that cannot be expressed as the product of two numbers of the form a + b*sqrt(-11), where a > 0 and b >= 0 (excluding 1 and n).

LINKS

Table of n, a(n) for n=1..58.

FORMULA

a(n) ~ 6/5 * n log n.

PROG

(MAGMA) Sort([11] cat [p: p in PrimesUpTo(317) | NormEquation(11, p) eq false]);

CROSSREFS

Cf. A033209.

Sequence in context: A329191 A154363 A049555 * A052042 A245576 A086472

Adjacent sequences:  A281292 A281293 A281294 * A281296 A281297 A281298

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Jan 19 2017

STATUS

approved

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Last modified January 21 22:54 EST 2021. Contains 340359 sequences. (Running on oeis4.)