A153144
Numbers n such that 2*n+19 is not a prime.
Original entry on oeis.org
1, 3, 4, 7, 8, 10, 13, 15, 16, 18, 19, 22, 23, 25, 28, 29, 31, 33, 34, 36, 37, 38, 40, 43, 46, 48, 49, 50, 51, 52, 53, 55, 57, 58, 61, 62, 63, 64, 67, 68, 70, 71, 73, 75, 76, 78, 79, 82, 83, 84, 85, 88, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101
Offset: 1
A155546
Triangle read by rows where T(m,n)=2mn + m + n - 5, 1<=n<=m.
Original entry on oeis.org
-1, 2, 7, 5, 12, 19, 8, 17, 26, 35, 11, 22, 33, 44, 55, 14, 27, 40, 53, 66, 79, 17, 32, 47, 62, 77, 92, 107, 20, 37, 54, 71, 88, 105, 122, 139, 23, 42, 61, 80, 99, 118, 137, 156, 175, 26, 47, 68, 89, 110, 131, 152, 173, 194, 215, 29, 52, 75, 98, 121, 144, 167, 190, 213
Offset: 1
Triangle begins:
-1;
2, 7;
5, 12, 19;
8, 17, 26, 35;
11, 22, 33, 44, 55;
14, 27, 40, 53, 66, 79;
17, 32, 47, 62, 77, 92, 107;
20, 37, 54, 71, 88, 105, 122, 139;
23, 42, 61, 80, 99, 118, 137, 156, 175;
26, 47, 68, 89, 110, 131, 152, 173, 194, 215; etc.
-
[2*n*k + n + k - 5: k in [1..n], n in [1..11]]; // Vincenzo Librandi, Nov 21 2012
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t[n_,k_]:= 2 n*k + n + k - 5; Table[t[n, k], {n, 15}, {k, n}]//Flatten (* Vincenzo Librandi, Nov 21 2012 *)
A153082
Numbers k such that 2*k + 13 is not prime.
Original entry on oeis.org
1, 4, 6, 7, 10, 11, 13, 16, 18, 19, 21, 22, 25, 26, 28, 31, 32, 34, 36, 37, 39, 40, 41, 43, 46, 49, 51, 52, 53, 54, 55, 56, 58, 60, 61, 64, 65, 66, 67, 70, 71, 73, 74, 76, 78, 79, 81, 82, 85, 86, 87, 88, 91, 94, 95, 96, 97, 98, 100, 101, 102, 103, 104, 106, 109, 111
Offset: 1
Distribution in the following triangular array:
*;
1, 6;
4, 11,18;
7, 16,25,34;
10,21,32,43,54;
13,26,39,52,65,78;
16,31,46,61,76,91,106;
19,36,53,70,87,104,121,138;
22,41,60,79,98,117,136,155,174;
25,46,67,88,109,130,151,172,193,214;
28,51,74,97,120,143,166,189,212,235,258;
31,56,81,106,131,156,181,206,231,256,281,306;
34,61,88,115,142,169,196,223,250,277,304,331,358; etc.
where * marks the negative values of (2*h*k + k + h - 6) with h >= k >= 1. -
_Vincenzo Librandi_, Jan 15 2013
Showing 1-3 of 3 results.
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