A063479 Numbers k such that omega(k+1) = 2*omega(k), where omega is the number of distinct prime factors.

5, 9, 11, 13, 17, 19, 23, 25, 27, 32, 37, 43, 47, 49, 53, 61, 64, 67, 71, 73, 79, 81, 97, 103, 107, 121, 128, 151, 157, 163, 191, 193, 199, 209, 211, 223, 241, 243, 271, 277, 283, 313, 329, 331, 337, 343, 361, 367, 383, 397, 421, 431, 457, 463, 487, 499, 512

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Example

omega(209)=2, omega(209+1)=2*2, so 209 is a term of the sequence.

Prog

(PARI) j=[]; for(n=1, 700, if(omega(n+1)==2*omega(n), j=concat(j, n))); j
(PARI) { n=0; for (m=1, 10^9, if (omega(m + 1) == 2*omega(m), write("b063479.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 23 2009

Crossrefs

Sequence in context: A043749 A043757 A043766 * A161155 A337920 A314585

Adjacent sequences: A063476 A063477 A063478 * A063480 A063481 A063482

Keyword

easy,nonn

Author

Jason Earls, Jul 28 2001

Status

approved