A065856 The (2^n)-th composite number.

4, 6, 9, 15, 26, 48, 88, 168, 323, 627, 1225, 2406, 4736, 9351, 18504, 36655, 72730, 144450, 287147, 571208, 1136971, 2264215, 4510963, 8990492, 17923944, 35743996, 71298762, 142249762, 283859985, 566537515, 1130886504, 2257704401, 4507834166, 9001524190

Offset

0,1

Comments

a(n) = A002808(A000079(n)).

Links

Chai Wah Wu, Table of n, a(n) for n = 0..70

Formula

a(n)-pi(a(n))-1 = 2^n.

Example

composite[1] = composite[2^0] = 4, composite[2] = composite[2^1] = 6, composite[1024] = composite[2^10] = 1225, composite[1073741824] = composite[2^30] = 1130886504.

Mathematica

Composite[n_Integer] := Block[ {k = n + PrimePi[n] + 1 }, While[ k != n + PrimePi[k] + 1, k = n + PrimePi[k] + 1]; Return[ k ]]; Table[ Composite[2^n], {n, 0, 36} ]

Crossrefs

Cf. A033844, A002808, A062298, A000720, A065855.

Sequence in context: A033476 A183978 A118696 * A136357 A136356 A136358

Adjacent sequences: A065853 A065854 A065855 * A065857 A065858 A065859

Keyword

nonn

Author

Labos Elemer, Nov 26 2001

Extensions

More terms from Robert G. Wilson v, Nov 26 2001

Definition corrected by N. J. A. Sloane, Jun 07 2009

Further corrections from Reinhard Zumkeller, Jun 24 2009

a(32)-a(33) from Chai Wah Wu, Apr 16 2018

Status

approved