1,1

Union of A039787 and A049097; complement of A075432 in A000040.

Enrique PĂ©rez Herrero, Table of n, a(n) for n = 1..1000

a(3) = 5 because 6 (the number above) is squarefree.

a(13) = 47 because 46 (the number below) is squarefree.

53 is not in the sequence because both 52 and 54 have squares among their divisors.

(Sage) def is_A075430(n): return is_prime(n) and (is_squarefree(n-1) or is_squarefree(n+1))

# [D. S. McNeil, Jan 16 2011]

Cf. A005117, A000040.

Sequence in context: A296236 A334041 A181172 * A095080 A229289 A087634

Adjacent sequences: A075427 A075428 A075429 * A075431 A075432 A075433

nonn

Reinhard Zumkeller, Sep 15 2002

approved