|
|
A117082
|
|
Octagonal numbers for which the sum of the digits is also an octagonal number.
|
|
1
|
|
|
0, 1, 8, 341, 1160, 4485, 6816, 9633, 12936, 16725, 20501, 25761, 30401, 36741, 42960, 64533, 81345, 90480, 131880, 143445, 168033, 181056, 208560, 238008, 253461, 269400, 302736, 338016, 375240, 414408, 434721, 455520, 520833, 590520
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
EXAMPLE
|
1160 is in the sequence because (1) it is a octagonal number and (2)the sum of its digits 1+1+6+0=8 is also a octagonal number.
|
|
MATHEMATICA
|
octQ[n_] := IntegerQ[(Sqrt[3 n + 1] + 1)/3]; t = {0}; Do[x = n*(3 n - 2); If[octQ[Plus @@ IntegerDigits[x]], AppendTo[t, x]], {n, 450}]; t (* Jayanta Basu, Jul 13 2013 *)
With[{oct=PolygonalNumber[8, Range[0, 500]]}, Select[oct, MemberQ[oct, Total[ IntegerDigits[ #]]]&]] (* The program uses the PolygonalNumber function from Mathematica version 10 *) (* Harvey P. Dale, Mar 06 2016 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Luc Stevens (lms022(AT)yahoo.com), Apr 17 2006
|
|
STATUS
|
approved
|
|
|
|