|
Search: id:A081978
|
|
|
| A081978 |
|
Smallest triangular number with n divisors, or 0 if no such number exists. |
|
+0
2
|
|
| 1, 3, 0, 6, 0, 28, 0, 66, 36, 496, 0, 276, 0, 378, 1631432881, 120, 0, 300, 0
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
FORMULA
|
a(p)=0 if p is an odd prime. If n is an odd composite number, then a(n) is a square; see A001110 for numbers that are both triangular and square. - Victoria Sapko (vsapko(AT)frc.mass.edu), Sep 28 2007
|
|
EXAMPLE
|
a(2)=3 because the smallest triangular number with 2 divisors is T(2)=3.
|
|
CROSSREFS
|
Cf. A081979.
Cf. A001110.
Sequence in context: A007386 A007385 A022899 this_sequence A117784 A111074 A007384
Adjacent sequences: A081975 A081976 A081977 this_sequence A081979 A081980 A081981
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 03 2003
|
|
EXTENSIONS
|
More terms from Victoria Sapko (vsapko(AT)frc.mass.edu), Sep 28 2007
|
|
|
Search completed in 0.002 seconds
|
