OFFSET
1,1
COMMENTS
Numbers n such that n is admirable, n-1 is prime and n+1 is prime.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
30 is in the sequence, as 29=30-1 and 31=30+1 are a pair of twin primes.
MATHEMATICA
Select[Range[18000], MemberQ[Most[Divisors[#]], (DivisorSigma[1, #]-2#)/2]&&AllTrue[#+{1, -1}, PrimeQ]&] (* Harvey P. Dale, Sep 11 2023 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Olaf Voß, Feb 09 2008
STATUS
approved