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A131101 Numbers that when added it to their prime factors +1 the result is a prime number, member of A131102. 1
1, 2, 3, 5, 11, 23, 27, 29, 30, 32, 36, 41, 53, 60, 66, 75, 78, 83, 89, 113, 114, 117, 130, 131, 132, 138, 140, 171, 173, 175, 179, 186, 191, 204, 220, 233, 239, 240, 246, 251, 255, 258, 260, 276, 279, 281, 285, 286, 293, 308, 310, 325, 338, 340, 354, 359, 363 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The Sophie Germain prime numbers (A005384) are part of this sequence because when adding to one of them its only prime factor (itself) + 1 = 2*A005384 + 1 the result is another prime number (A005385)

LINKS

Table of n, a(n) for n=1..57.

FORMULA

a(n)+ prime factors of a(n) + 1 = p ; p is a prime number, member of A131102.

EXAMPLE

a(8)=29 because 29 + its only prime factor (itself) + 1 = 29+29+1= 59, and 59 is a prime number = A131102(8) = A005385(6).

a(9)=30 because 30 + its prime factors + 1 = 30 +(2+3+5)+1 =41, and 41 is a prime number = A131102(9).

CROSSREFS

Sequence in context: A073880 A118332 A118333 * A188534 A214196 A246857

Adjacent sequences:  A131098 A131099 A131100 * A131102 A131103 A131104

KEYWORD

easy,nonn

AUTHOR

Tomas Xordan, Jun 14 2007

STATUS

approved

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Last modified January 22 07:39 EST 2020. Contains 331139 sequences. (Running on oeis4.)