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A067738 Numbers n such that sigma(n)+sigma(sigma(n)) is prime. 0
1, 2, 3, 7, 22, 32, 49, 52, 66, 70, 93, 94, 97, 98, 115, 119, 121, 127, 169, 170, 196, 214, 241, 242, 256, 265, 337, 343, 364, 441, 450, 513, 529, 567, 577, 578, 597, 679, 723, 784, 800, 841, 967, 1058, 1225, 1249, 1369, 1444, 1521, 1682, 1731, 1802, 1849 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..53.

MATHEMATICA

Select[Range[2000], PrimeQ[DivisorSigma[1, #]+DivisorSigma[1, DivisorSigma[ 1, #]]]&] (* Harvey P. Dale, Apr 02 2018 *)

CROSSREFS

Sequence in context: A001532 A109456 A155745 * A296287 A187014 A053966

Adjacent sequences:  A067735 A067736 A067737 * A067739 A067740 A067741

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Feb 23 2002

STATUS

approved

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Last modified April 19 08:59 EDT 2021. Contains 343110 sequences. (Running on oeis4.)