A144670 - OEIS

A144670

Triangle read by rows where T(m,n)=2mn+m+n-7

-3, 0, 5, 3, 10, 17, 6, 15, 24, 33, 9, 20, 31, 42, 53, 12, 25, 38, 51, 64, 77, 15, 30, 45, 60, 75, 90, 105, 18, 35, 52, 69, 86, 103, 120, 137, 21, 40, 59, 78, 97, 116, 135, 154, 173, 24, 45, 66, 87, 108, 129, 150, 171, 192, 213, 27, 50, 73, 96, 119, 142, 165, 188, 211, 234, 257

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OFFSET

1,1

COMMENTS

Numbers n such that, if 2^(s-1)=n then [A144487] is not prime.

Let p (prime number), n=(p^2-15)/2 mod(p).

LINKS

Vincenzo Librandi, Rows n = 100, flattened

EXAMPLE

Triangle begins:

-3;

0, 5;

3, 10, 17;

6, 15, 24, 33;

9, 20, 31, 42, 53;

12, 25, 38, 51, 64, 77;

15, 30, 45, 60, 75, 90, 105;

18, 35, 52, 69, 86, 103, 120, 137;

21, 40, 59, 78, 97, 116, 135, 154, 173;

24, 45, 66, 87, 108, 129, 150, 171, 192, 213;

= = = = = = = =

MATHEMATICA

t[n_, k_]:=2 n*k+n+k-7; Table[t[n, k], {n, 12}, {k, n}] // Flatten (* Vincenzo Librandi, Oct 15 2012 *)

PROG

(Magma) [2*n*k + n + k -7: k in [1..n], n in [1..12]]; // Vincenzo Librandi, Oct 15 2012

CROSSREFS

Cf. A057197, A144487.

Sequence in context: A225744 A275393 A029840 * A370549 A011078 A354592

Adjacent sequences: A144667 A144668 A144669 * A144671 A144672 A144673

KEYWORD

tabl,sign

AUTHOR

Vincenzo Librandi, Jan 28 2009

STATUS

approved