A154684 - OEIS

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A154684

Triangle read by rows where T(m,n)=2mn + m + n - 3, 1<=n<=m.

4

1, 4, 9, 7, 14, 21, 10, 19, 28, 37, 13, 24, 35, 46, 57, 16, 29, 42, 55, 68, 81, 19, 34, 49, 64, 79, 94, 109, 22, 39, 56, 73, 90, 107, 124, 141, 25, 44, 63, 82, 101, 120, 139, 158, 177, 28, 49, 70, 91, 112, 133, 154, 175, 196, 217, 31, 54, 77, 100, 123, 146, 169

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

2*T(m,n)+7 = (2n+1)*(2m+1) is not prime.

First column: A016777; second column: A016897; third column: A008589; fourth column: A017173. - Vincenzo Librandi, Nov 19 2012

LINKS

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

EXAMPLE

Triangle begins:

1;

4, 9;

7, 14, 21;

10, 19, 28, 37;

13, 24, 35, 46, 57;

16, 29, 42, 55, 68, 81;

19, 34, 49, 64, 79, 94, 109;

22, 39, 56, 73, 90, 107, 124, 141;

25, 44, 63, 82, 101, 120, 139, 158, 177;

28, 49, 70, 91, 112, 133, 154, 175, 196, 217; etc.

MATHEMATICA

t[n_, k_]:=2 n*k + n + k - 3; Table[t[n, k], {n, 20}, {k, n}]//Flatten (* Vincenzo Librandi, Nov 19 2012 *)

PROG

(Magma) [(2*n*k + n + k - 3): k in [1..n], n in [1..11]]; // Vincenzo Librandi, Nov 19 2012

CROSSREFS

Cf. A153053, A105760, A162265 (row sums), A016777, A016897, A008589, A017173.

Sequence in context: A338304 A179222 A123157 * A353071 A365906 A256174

Adjacent sequences: A154681 A154682 A154683 * A154685 A154686 A154687

KEYWORD

nonn,tabl,easy

AUTHOR

Vincenzo Librandi, Jan 18 2009

STATUS

approved