A025000 a(1) = 3; a(n+1) = a(n)-th nonprime, where nonprimes begin at 0.

3, 4, 6, 9, 14, 21, 30, 42, 57, 77, 102, 133, 171, 217, 274, 341, 422, 518, 632, 766, 922, 1106, 1320, 1565, 1846, 2171, 2541, 2967, 3447, 3996, 4618, 5321, 6117, 7018, 8027, 9162, 10438, 11858, 13450, 15225, 17205, 19400, 21849, 24573, 27584, 30916, 34612

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..1249

Mathematica

Module[{nn=60000, npr}, npr=Complement[Range[0, nn], Prime[ Range[ PrimePi[ nn]]]]; NestList[npr[[#]]&, 3, 50]] (* Harvey P. Dale, Dec 13 2014 *)

Prog

(Python)
from sympy import composite
def A025000(n): return 3 if n == 1 else composite(A025000(n-1)-2) # Chai Wah Wu, Apr 30 2026

Crossrefs

Sequence in context: A352095 A030712 A387137 * A147790 A048577 A107340

Adjacent sequences: A024997 A024998 A024999 * A025001 A025002 A025003

Keyword

nonn

Author

David W. Wilson

Status

approved