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A102343 Numbers n such that n*10^3+777 is prime. 0
1, 2, 11, 19, 22, 26, 41, 43, 44, 47, 50, 53, 65, 67, 68, 71, 76, 79, 80, 83, 94, 97, 107, 110, 113, 115, 122, 124, 125, 131, 134, 136, 137, 145, 146, 152, 155, 158, 167, 169, 170, 173, 176, 181, 184, 199, 202, 211, 212, 226, 229, 232, 233, 250, 253, 254, 268, 272, 274, 281, 284, 286, 292, 295, 298, 299 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The sequence is infinite, because by Dirichlet's theorem there are infinitely many primes in the arithmetic sequence A*n+B (n=1,2,...) if A an B are relatively prime. [Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 27 2009]

No term of the sequence is of form 3k, because the sum of digits of 10^3*3k+333=3*(10^3+259) is divisible by 3, violating the requirement of the definition. [Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 27 2009]

LINKS

Table of n, a(n) for n=1..66.

EXAMPLE

n=1: 1*10^3+777 = 1777 is prime, hence 1 is in the sequence.

n=50: 50*10^3+777 = 50777 is prime, hence 50 is in the sequence.

n=97: 97*10^3+777 = 97777 is prime, hence 97 is in the sequence.

PROG

(MAGMA) [ n: n in [0..300] | IsPrime(n*10^3+777) ];

(PARI) is(n)=isprime(n*10^3+777) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A157772, A102248, A159942. [Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 27 2009]

Sequence in context: A121848 A074926 A066144 * A023173 A018443 A163058

Adjacent sequences:  A102340 A102341 A102342 * A102344 A102345 A102346

KEYWORD

nonn,base,easy

AUTHOR

Parthasarathy Nambi, Feb 20 2005

EXTENSIONS

Extended by Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 27 2009

Edited by R. J. Mathar, Apr 30 2009

More terms from Vincenzo Librandi, May 01 2009

STATUS

approved

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Last modified December 8 01:57 EST 2019. Contains 329850 sequences. (Running on oeis4.)