A153040 -id:A153040 - cp's OEIS frontend

A153043 Numbers n > 1 such that 2*n-3 is not a prime.

2, 6, 9, 12, 14, 15, 18, 19, 21, 24, 26, 27, 29, 30, 33, 34, 36, 39, 40, 42, 44, 45, 47, 48, 49, 51, 54, 57, 59, 60, 61, 62, 63, 64, 66, 68, 69, 72, 73, 74, 75, 78, 79, 81, 82, 84, 86, 87, 89, 90, 93, 94, 95, 96, 99, 102, 103, 104, 105, 106, 108, 109, 110

Offset: 1

Vincenzo Librandi, Dec 17 2008

One more than the associated value in A104275. - R. J. Mathar, Jan 05 2011
2*A155705(m,n)-3 = (2n+1)*(2m+1) are nonprime: all A155705(.,.) are in this sequence.
The terms after a(1) are the values of 2*h*k + k + h + 2, where h and k are positive integers. - Vincenzo Librandi, Jan 19 2013

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Cf. A098090, A104275, A153040, A155705.

[n: n in [2..102] | not IsPrime(2*n-3)];  // Bruno Berselli, Mar 05 2011

Select[Range[2,200], !PrimeQ[2*#-3]&] (* Vladimir Joseph Stephan Orlovsky, Feb 09 2012 *)

A153039 Numbers k such that 2*k-7 is composite.

Original entry on oeis.org

8, 11, 14, 16, 17, 20, 21, 23, 26, 28, 29, 31, 32, 35, 36, 38, 41, 42, 44, 46, 47, 49, 50, 51, 53, 56, 59, 61, 62, 63, 64, 65, 66, 68, 70, 71, 74, 75, 76, 77, 80, 81, 83, 84, 86, 88, 89, 91, 92, 95, 96, 97, 98, 101, 104, 105, 106, 107, 108, 110, 111, 112

Offset: 1

Vincenzo Librandi, Dec 17 2008

Two more than the associated value in A153043, one more than in A153040.

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Complement of A089192, A153040.

[n: n in [5..220]| not IsPrime(2*n-7)];

Select[Range[8,200], !PrimeQ[2*#-7]&] (* Vladimir Joseph Stephan Orlovsky, Feb 09 2012 *)

list(n)=apply(k->(k+7)/2,setminus(vector(n,k,2*k+7), primes(primepi(2*n+7)))) \\ Charles R Greathouse IV, May 14 2012

Partially edited by N. J. A. Sloane, Jun 23 2010

A153041 Numbers n >=10 such that 2*n-19 is not a prime.

Original entry on oeis.org

10, 14, 17, 20, 22, 23, 26, 27, 29, 32, 34, 35, 37, 38, 41, 42, 44, 47, 48, 50, 52, 53, 55, 56, 57, 59, 62, 65, 67, 68, 69, 70, 71, 72, 74, 76, 77, 80, 81, 82, 83, 86, 87, 89, 90, 92, 94, 95, 97, 98, 101, 102, 103, 104

Offset: 1

Vincenzo Librandi, Dec 17 2008

One more than associated values in A153051, two more than A153047. - R. J. Mathar, Jan 05 2011

The terms after a(1) are the values of 2*h*k + k + h + 10, where h and k are positive integers.- Vincenzo Librandi, Jan 19 2013

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Cf. A097932, A155704.
Numbers n such that 2n-k is not prime: A104275 (k=1), A153043 (k=3), A153040 (k=5), A153039 (k=7), A153044 (k=9), A153045 (k=11), A153049 (k=13), A153047 (k=15), A153051 (k=17), A153041 (k=19).
Similar sequence listed also in A089559, A153144.

[n: n in [10..150] | not IsPrime(2*n - 19)]; // Vincenzo Librandi, Jan 19 2013

Select[Range[10, 200], !PrimeQ[2 # - 19] &] (* Vincenzo Librandi, Jan 19 2013 *)

Edited by N. J. A. Sloane, Jun 22 2010

A154681 Triangle read by rows where T(m,n) = 2mn + m + n +3.

Original entry on oeis.org

7, 10, 15, 13, 20, 27, 16, 25, 34, 43, 19, 30, 41, 52, 63, 22, 35, 48, 61, 74, 87, 25, 40, 55, 70, 85, 100, 115, 28, 45, 62, 79, 96, 113, 130, 147, 31, 50, 69, 88, 107, 126, 145, 164, 183, 34, 55, 76, 97, 118, 139, 160, 181, 202, 223, 37, 60, 83, 106, 129, 152

Offset: 1

Vincenzo Librandi, Jan 18 2009

2*T(m,n) - 5 = (2*n+1)*(2*m+1) is not prime.

First column: A112414; second column: A008587.

			Triangle begins:
  7;
  10, 15;
  13, 20, 27;
  16, 25, 34, 43;
  19, 30, 41, 52,  63;
  22, 35, 48, 61,  74,  87;
  25, 40, 55, 70,  85, 100, 115;
  28, 45, 62, 79,  96, 113, 130, 147;
  31, 50, 69, 88, 107, 126, 145, 164, 183;
  34, 55, 76, 97, 118, 139, 160, 181, 202, 223; etc.

Vincenzo Librandi, Rows n = 1..100, flattened

Cf. A153040, A008587, A089253, A112414.

[(2*n*k + n + k + 3): k in [1..n], n in [1..11]]; // Vincenzo Librandi, Nov 17 2012

t[n_,k_]:=2 n*k + n + k + 3; Table[t[n, k], {n, 10}, {k, n}]//Flatten (* vincenzo Librandi, Nov 17 2012 *)

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A153043 Numbers n > 1 such that 2*n-3 is not a prime.

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A153039 Numbers k such that 2*k-7 is composite.

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A153041 Numbers n >=10 such that 2*n-19 is not a prime.

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A154681 Triangle read by rows where T(m,n) = 2*m*n + m + n +3.

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A154681 Triangle read by rows where T(m,n) = 2mn + m + n +3.