A116050 - OEIS

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A116050

n+sigma(n)+sigma(sigma(n)) is a prime.

1, 4, 5, 8, 10, 16, 18, 22, 23, 27, 29, 32, 36, 41, 46, 50, 53, 65, 66, 70, 94, 99, 101, 106, 111, 113, 125, 129, 131, 137, 171, 183, 195, 197, 200, 201, 203, 209, 210, 221, 233, 237, 239, 245, 251, 269, 275, 299, 301, 309, 317, 321, 322, 327, 329, 333, 335

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

8 + sigma(8) + sigma(sigma(8)) = 47.

MATHEMATICA

dsQ[n_]:=Module[{dsn=DivisorSigma[1, n]}, PrimeQ[n+dsn+DivisorSigma[1, dsn]]]; Select[Range[400], dsQ] (* Harvey P. Dale, May 15 2013 *)

CROSSREFS

Cf. A078762.

Sequence in context: A295068 A022435 A190394 * A241413 A056721 A057479

Adjacent sequences: A116047 A116048 A116049 * A116051 A116052 A116053

KEYWORD

nonn

AUTHOR

Giovanni Resta, Feb 13 2006

STATUS

approved