A088070 Numbers sandwiched between two numbers having the same number of prime divisors.

3, 4, 6, 8, 10, 11, 12, 13, 18, 19, 21, 23, 24, 25, 26, 27, 28, 30, 34, 35, 37, 39, 42, 45, 47, 48, 49, 51, 53, 55, 56, 57, 60, 64, 72, 73, 75, 76, 80, 81, 82, 86, 87, 92, 93, 94, 95, 97, 99, 102, 105, 107, 108, 116, 117, 118, 123, 126, 131, 134, 135, 138, 139, 142, 143, 144

Offset: 1

Author

Amarnath Murthy, Sep 22 2003

Keywords

• nonn

Comments

Subsidiary sequence: (1) Start of the first run of a string of n successive integers in this sequence. Conjecture: For every k there is a string of k successive integers.

Examples

			11 is a member as 10 and 12 both have two prime divisors.
26 is a member as 25 and 27 both have one each prime divisor.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A063464.

Programs

PARI

isok(n) = omega(n-1) == omega(n+1); \\ Michel Marcus, Oct 18 2016

Formula

a(n) = A063464(n) + 1.

Extensions

More terms from Ray Chandler, Sep 27 2003

Offset corrected and formula adapted by Michel Marcus, Oct 18 2016