OFFSET
1,1
COMMENTS
Terms k such that k+1 is also in this sequence are 22625, 28375, 40472, ...
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
Numbers n such that both n and n+1 are of the form p^3 * q * r * s * ... where p, q, r, ... are distinct primes (with zero or more primes q, r, s, ...). - Charles R Greathouse IV, Jun 05 2020
EXAMPLE
135 is a term since both 135 and 136 have 4 unitary divisors and 4 nonunitary divisors.
MATHEMATICA
seqQ[n_] := DivisorSigma[0, n] == 2^(PrimeNu[n] + 1); q1 = seqQ[1]; s = {}; Do[q2 = seqQ[n]; If[q1 && q2, AppendTo[s, n-1]]; q1 = q2, {n, 2, 10^4}]; s
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jun 01 2020
STATUS
approved