The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A144652 Triangle, read by rows, where T(m,n) = floor((2mn+m+n)/2) with m >= n >= 1. 1
2, 3, 6, 5, 8, 12, 6, 11, 15, 20, 8, 13, 19, 24, 30, 9, 16, 22, 29, 35, 42, 11, 18, 26, 33, 41, 48, 56, 12, 21, 29, 38, 46, 55, 63, 72, 14, 23, 33, 42, 52, 61, 71, 80, 90, 15, 26, 36, 47, 57, 68, 78, 89, 99, 110, 17, 28, 40, 51, 63, 74, 86, 97, 109, 120, 132, 18, 31, 43, 56, 68 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
From Vincenzo Librandi, Nov 16 2012: (Start)
First column: A007494(n+1);
second column: A047219(n+2);
third column: A047383(n+3);
fourth column: A193910(n+4).
Conjecture: If h does not belong to the sequence, then 4*h+1 is prime. (End)
LINKS
Vincenzo Librandi, Rows n = 1..100, flattened
EXAMPLE
Triangle begins:
2;
3, 6;
5, 8, 12;
6, 11, 15, 20;
8, 13, 19, 24, 30;
9, 16, 22, 29, 35, 42;
11, 18, 26, 33, 41, 48, 56; etc.
MATHEMATICA
Flatten[Table[Floor[(2*n*m + m + n)/2], {n, 1, 20}, {m, n}]] (* Vincenzo Librandi, Nov 16 2012 *)
PROG
(Magma) [Floor((2*n*k+n+k)/2): k in [1..n], n in [1..11]]; // Vincenzo Librandi, Nov 16 2012
CROSSREFS
Sequence in context: A276081 A329564 A257011 * A035493 A363277 A070038
KEYWORD
nonn,tabl,easy
AUTHOR
Vincenzo Librandi, Jan 27 2009
EXTENSIONS
Definition edited (specifying m >= n >= 1), and terms recomputed to match definition, as was done with the similar sequence A140869, by Jon E. Schoenfield, Jun 24 2010
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 27 18:18 EDT 2024. Contains 372880 sequences. (Running on oeis4.)