|
|
A115887
|
|
Triangular numbers equal to the difference between a prime number and its index.
|
|
2
|
|
|
1, 3, 6, 10, 28, 105, 120, 153, 231, 465, 496, 1081, 1378, 1485, 1653, 1711, 2628, 3003, 3081, 3160, 4950, 5050, 5460, 6670, 6903, 8001, 8778, 10296, 11781, 14028, 15225, 16290, 19701, 20503, 21528, 21945, 22155, 24310, 24531, 25200, 27495
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
28=T(7)=p(13)-13.
|
|
MATHEMATICA
|
Union[Select[Table[Prime[i]-i, {i, 20000}], IntegerQ[Sqrt[8#+1]]&]] (* Harvey P. Dale, Jun 28 2012 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|