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A185208 Numbers having no divisors d > 1 such that d + 1 are prime powers. 5
1, 5, 11, 13, 17, 19, 23, 25, 29, 37, 41, 43, 47, 53, 55, 59, 61, 65, 67, 71, 73, 79, 83, 85, 89, 95, 97, 101, 103, 107, 109, 113, 115, 121, 125, 131, 137, 139, 143, 145, 149, 151, 157, 163, 167, 169, 173, 179, 181, 185, 187, 191, 193, 197, 199, 205, 209 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A141197(a(n)) = A049073(a(n)) = 1.

Contains all primes except for 2 and Mersenne primes A000668. - Jon Perry, Nov 11 2012

A composite number is in the sequence iff all its factors are. - Jon Perry, Nov 11 2012

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[210], Select[Divisors[#] // Rest, PrimeNu[# + 1] == 1 &] == {} &] (* Jean-Fran├žois Alcover, Aug 17 2013 *)

PROG

(Haskell)

a185208 n = a185208_list !! (n-1)

a185208_list =  filter ((== 1) . a141197) [1..]

CROSSREFS

Cf. A000961, A010055, A027750.

Cf. A000668.

Sequence in context: A206548 A206547 A295584 * A216227 A020611 A156312

Adjacent sequences:  A185205 A185206 A185207 * A185209 A185210 A185211

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 01 2012

STATUS

approved

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Last modified September 30 05:03 EDT 2020. Contains 337435 sequences. (Running on oeis4.)