|
Search: id:A124199
|
|
|
| A124199 |
|
Primes of the form k(k+1)/2-2 (i.e. two less than triangular numbers). |
|
+0
1
|
|
| 13, 19, 43, 53, 89, 103, 151, 229, 251, 349, 433, 463, 593, 701, 739, 859, 1033, 1223, 1429, 1483, 1709, 1889, 1951, 2143, 2699, 3001, 3079, 3319, 3739, 4003, 4093, 4463, 4751, 5563, 5669, 6553, 7019, 7873, 8513, 9043, 10009, 10151, 10729, 11173, 11779
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
The (first five triangular numbers)-2 are: -1,1,4,8,13. So a(1)=13 is the first prime of this form.
|
|
MATHEMATICA
|
Pick[ #1, PrimeQ[ #1]]&[((1/2)*#1*(#1 + 1) - 2 & ) /@ Range[180]]
|
|
CROSSREFS
|
Cf. A055472.
Sequence in context: A029478 A102907 A096455 this_sequence A119869 A106904 A106903
Adjacent sequences: A124196 A124197 A124198 this_sequence A124200 A124201 A124202
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Peter Pein (petsie(AT)dordos.net), Dec 07 2006
|
|
|
Search completed in 0.002 seconds
|
