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
A162257
a(n) = (2*n^3 + 5*n^2 - 11*n)/2.
Original entry on oeis.org
-2, 7, 33, 82, 160, 273, 427, 628, 882, 1195, 1573, 2022, 2548, 3157, 3855, 4648, 5542, 6543, 7657, 8890, 10248, 11737, 13363, 15132, 17050, 19123, 21357, 23758, 26332, 29085, 32023, 35152, 38478, 42007, 45745, 49698, 53872, 58273, 62907, 67780
Offset: 1
-
A162257:=n->(2*n^3+5*n^2-11*n)/2: seq(A162257(n), n=1..80); # Wesley Ivan Hurt, Jan 30 2017
-
CoefficientList[Series[(-2+15*x-7*x^2)/(1-x)^4,{x,0,40}],x] (* or *) LinearRecurrence[{4, -6, 4, -1}, {-2, 7, 33, 82}, 50] (* Vincenzo Librandi, Mar 04 2012 *)
A324937
Triangle read by rows: T(n, k) = 2*n*k + n + k - 8.
Original entry on oeis.org
-4, -1, 4, 2, 9, 16, 5, 14, 23, 32, 8, 19, 30, 41, 52, 11, 24, 37, 50, 63, 76, 14, 29, 44, 59, 74, 89, 104, 17, 34, 51, 68, 85, 102, 119, 136, 20, 39, 58, 77, 96, 115, 134, 153, 172, 23, 44, 65, 86, 107, 128, 149, 170, 191, 212, 26, 49, 72, 95, 118, 141, 164, 187, 210, 233, 256
Offset: 1
Triangle begins:
-4;
-1, 4;
2, 9, 16;
5, 14, 23, 32;
8, 19, 30, 41, 52;
11, 24, 37, 50, 63, 76;
14, 29, 44, 59, 74, 89, 104;
17, 34, 51, 68, 85, 102, 119, 136;
20, 39, 58, 77, 96, 115, 134, 153, 172; etc.
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[2*n*k+n+k-8: k in [1..n], n in [1..11]]; /* As triangle */ [[2*n*k+n+k-8: k in [1..n]]: n in [1.. 15]];
-
t[n_, k_]:=2 n k + n + k - 8; Table[t[n, k], {n, 11}, {k, n}]//Flatten
Showing 1-3 of 3 results.
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