|
|
A117309
|
|
Triangular numbers for which the sum of the digits is a hexagonal number.
|
|
1
|
|
|
0, 1, 6, 10, 15, 78, 105, 231, 276, 465, 528, 780, 861, 1176, 1275, 1653, 1770, 2211, 2346, 2850, 3003, 3570, 3741, 4371, 4560, 5253, 5460, 5995, 6216, 6441, 7260, 7503, 11175, 12246, 12561, 14028, 14878, 15225, 17205, 17578, 20301, 20706, 22155, 24090
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
EXAMPLE
|
105 is in the sequence because (1) it is a triangular number and (2) the sum of its digits 1+0+5=6 is a hexagonal number.
|
|
MATHEMATICA
|
Join[{0}, Select[Accumulate[Range[350]], IntegerQ[(1+Sqrt[8Total[ IntegerDigits[#]]+1])/4]&]] (* Harvey P. Dale, Jun 06 2011 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Luc Stevens (lms022(AT)yahoo.com), Apr 26 2006
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|