A077656 Numbers having a different number of prime factors as their successors (counted with multiplicity).

1, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 22, 23, 24, 26, 28, 29, 30, 31, 32, 35, 36, 37, 39, 40, 41, 42, 43, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 76, 77, 78, 79, 80, 81, 82, 83

Offset

1,2

Comments

A077655(a(n))=0; A001222(a(n))<>A001222(a(n)+1).

Links

Table of n, a(n) for n=1..71.

Example

20=2*2*5 and 20+1=21=3*7: A001222(20)<>A001222(21), therefore 20 is a term (A077655(20)=0).

Mathematica

Position[Partition[PrimeOmega[Range[100]], 2, 1], _?(#[[1]]!=#[[2]]&), {1}, Heads->False]//Flatten (* Harvey P. Dale, Sep 19 2016 *)

Crossrefs

Cf. A001222, A045920.

Sequence in context: A184530 A304804 A359776 * A039236 A304808 A039180

Adjacent sequences: A077653 A077654 A077655 * A077657 A077658 A077659

Keyword

nonn

Author

Reinhard Zumkeller, Nov 13 2002

Status

approved