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A078762 Numbers n such that n + sigma(n) is prime. 6
1, 2, 3, 4, 5, 8, 11, 16, 21, 23, 27, 29, 35, 36, 41, 53, 55, 57, 63, 64, 65, 75, 77, 83, 85, 89, 98, 100, 111, 113, 119, 125, 128, 131, 133, 143, 144, 155, 161, 171, 173, 179, 183, 189, 191, 203, 205, 209, 215, 233, 235, 237, 239, 242, 243, 245, 251, 253, 259, 275 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Union of A005384 (Sophie Germain primes) and A249486. - Jaroslav Krizek, Nov 13 2014

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

select(t -> isprime(t+numtheory:-sigma(t)), [$1..1000]); # Robert Israel, May 01 2018

MATHEMATICA

Select[Range[10^3], PrimeQ[ # + DivisorSigma[1, # ]] &]

PROG

(PARI) for(n=1, 1000, if(isprime(sigma(n)+n), print1(n, ", "))) \\ Derek Orr, Nov 13 2014

CROSSREFS

Sequence in context: A271488 A333347 A302592 * A103262 A135318 A210671

Adjacent sequences:  A078759 A078760 A078761 * A078763 A078764 A078765

KEYWORD

nonn,easy

AUTHOR

Joseph L. Pe, Jan 08 2003

STATUS

approved

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Last modified July 24 23:25 EDT 2021. Contains 346273 sequences. (Running on oeis4.)