A163400 -id:A163400 - cp's OEIS frontend

A163405 a(n) = (n-th nonprime) + (number of bits in binary expansion of n-th nonprime).

1, 2, 7, 9, 12, 13, 14, 16, 18, 19, 21, 23, 25, 26, 27, 29, 30, 31, 32, 33, 35, 38, 39, 40, 41, 42, 44, 45, 46, 48, 50, 51, 52, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 66, 68, 69, 71, 72, 73, 75, 76, 77, 79, 81, 82, 83, 84, 85, 87, 88, 89, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101

Offset: 1

Juri-Stepan Gerasimov, Jul 26 2009

nonn

Here n-th nonprime = A141468(n) and n-th number of bits in binary expansion of n-th nonprime = A163400(n).

			a(1) = 1 (= 0+1);
a(2) = 2 (= 1+1);
a(3) = 7 (= 4+3).

Cf. A141468, A163400.

A141468 := proc(n) option remember; if n = 1 then 0; else for a from procname(n-1)+1 do if not isprime(a) then return a; fi; od: fi; end: A070939 := proc(n) max(1,ilog2(n)+1) ; end: A163400 := proc(n) A070939(A141468(n)) ; end: A163405 := proc(n) A141468(n)+A163400(n) ; end: seq(A163405(n),n=1..120) ; # R. J. Mathar, Oct 10 2009

a(n) ~ n. [Charles R Greathouse IV, Dec 21 2011]

A163406 Numbers n which are not in A163405.

Original entry on oeis.org

3, 4, 5, 6, 8, 10, 11, 15, 17, 20, 22, 24, 28, 34, 36, 37, 43, 47, 49, 53, 59, 65, 67, 70, 74, 78, 80, 86, 90, 96, 104, 108, 110, 114, 116, 120, 134, 135, 139, 145, 147, 157, 159, 165, 171, 175, 181, 187, 189, 199, 201, 205, 207, 219, 231, 235, 237, 241, 247, 249, 259

Offset: 1

Juri-Stepan Gerasimov, Jul 26 2009, Aug 10 2008

nonn

Cf. A141468, A163400, A163405.

Edited (but not checked) by N. J. A. Sloane, Aug 11 2009

70 inserted by R. J. Mathar, Oct 10 2009

cp's OEIS Frontend

A163405 a(n) = (n-th nonprime) + (number of bits in binary expansion of n-th nonprime).

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A163406 Numbers n which are not in A163405.

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