A053542 Distance from n-th composite number (A002808) to next prime.

1, 1, 3, 2, 1, 1, 3, 2, 1, 1, 3, 2, 1, 5, 4, 3, 2, 1, 1, 5, 4, 3, 2, 1, 3, 2, 1, 1, 3, 2, 1, 5, 4, 3, 2, 1, 5, 4, 3, 2, 1, 1, 5, 4, 3, 2, 1, 3, 2, 1, 1, 5, 4, 3, 2, 1, 3, 2, 1, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1, 3, 2, 1, 1, 3, 2, 1, 1, 3, 2, 1, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 3, 2, 1, 5, 4, 3, 2, 1

Offset

1,3

Links

Table of n, a(n) for n=1..103.

Formula

Beginning with 2, make sequence of composites; measure distances to next prime

Example

a(1)=4, composite; distance to next prime, 5, is 1.

Mathematica

Table[NextPrime[n]-n, {n, Select[Range[150], CompositeQ]}] (* Harvey P. Dale, Apr 28 2016 *)

Crossrefs

Cf. A002808.

Sequence in context: A010268 A181657 A172254 * A087284 A262311 A242950

Adjacent sequences: A053539 A053540 A053541 * A053543 A053544 A053545

Keyword

easy,nonn

Author

Enoch Haga, Jan 16 2000

Extensions

Edited by N. J. A. Sloane, Sep 09 2011

Status

approved