The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A065856 The (2^n)-th composite number. 5
 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 (list; graph; refs; listen; history; text; internal format)
 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 19 20:41 EST 2020. Contains 331066 sequences. (Running on oeis4.)