A155722
Numbers k such that 2*k + 9 is prime.
Original entry on oeis.org
1, 2, 4, 5, 7, 10, 11, 14, 16, 17, 19, 22, 25, 26, 29, 31, 32, 35, 37, 40, 44, 46, 47, 49, 50, 52, 59, 61, 64, 65, 70, 71, 74, 77, 79, 82, 85, 86, 91, 92, 94, 95, 101, 107, 109, 110, 112, 115, 116, 121, 124, 127, 130, 131, 134, 136, 137, 142, 149, 151, 152, 154, 161, 164
Offset: 1
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Filtered([0..200], k-> IsPrime(2*k+9)); # G. C. Greubel, May 21 2019
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[n: n in [0..200] | IsPrime(2*n+9)]; // Vincenzo Librandi, Sep 24 2012
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(Prime[Range[5, 100]] - 9)/2 (* Vladimir Joseph Stephan Orlovsky, Feb 08 2010 *)
Select[Range[0, 200], PrimeQ[2 # + 9]&] (* Vincenzo Librandi, Sep 24 2012 *)
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is(n)=isprime(2*n+9) \\ Charles R Greathouse IV, Jul 12 2016
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[n for n in (0..200) if is_prime(2*n+9) ] # G. C. Greubel, May 21 2019
A155724
Triangle read by rows: T(n, k) = 2*n*k + n + k - 4.
Original entry on oeis.org
0, 3, 8, 6, 13, 20, 9, 18, 27, 36, 12, 23, 34, 45, 56, 15, 28, 41, 54, 67, 80, 18, 33, 48, 63, 78, 93, 108, 21, 38, 55, 72, 89, 106, 123, 140, 24, 43, 62, 81, 100, 119, 138, 157, 176, 27, 48, 69, 90, 111, 132, 153, 174, 195, 216, 30, 53, 76, 99, 122, 145, 168, 191, 214, 237, 260
Offset: 1
Triangle begins:
0;
3, 8;
6, 13, 20;
9, 18, 27, 36;
12, 23, 34, 45, 56;
15, 28, 41, 54, 67, 80;
18, 33, 48, 63, 78, 93, 108;
21, 38, 55, 72, 89, 106, 123, 140;
24, 43, 62, 81, 100, 119, 138, 157, 176;
27, 48, 69, 90, 111, 132, 153, 174, 195, 216;
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/* Triangle: */ [[2*m*n+m+n-4: m in [1..n]]: n in [1..10]]; // Bruno Berselli, Aug 31 2012
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Flatten[Table[2 n m + m + n - 4, {n, 10}, {m, n}]] (* Vincenzo Librandi, Mar 01 2012 *)
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def A155724(n,k): return 2*n*k+n+k-4
print(flatten([[A155724(n,k) for k in range(1,n+1)] for n in range(1,16)])) # G. C. Greubel, Jan 21 2025
A153083
Numbers such that 2*n + 11 is not prime.
Original entry on oeis.org
2, 5, 7, 8, 11, 12, 14, 17, 19, 20, 22, 23, 26, 27, 29, 32, 33, 35, 37, 38, 40, 41, 42, 44, 47, 50, 52, 53, 54, 55, 56, 57, 59, 61, 62, 65, 66, 67, 68, 71, 72, 74, 75, 77, 79, 80, 82, 83, 86, 87, 88, 89, 92, 95, 96, 97, 98, 99, 101, 102, 103, 104, 105, 107, 110, 112
Offset: 1
Distribution of the terms in the following triangular array:
*
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;
29,52,75,98,121,144,167,190,213,236,259;
32,57,82,107,132,157,182,207,232,257,282,307;
where * marks the decimal values of (2*h*k + k + h - 5) with h >= k >= 1. - _Vincenzo Librandi_, Jan 16 2013
Showing 1-3 of 3 results.
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