|
|
A066758
|
|
Triangular numbers not divisible by 10 whose reverse is pentagonal.
|
|
0
|
|
|
0, 1, 15, 21, 62481, 67896, 2618616, 10095771, 10550121, 5491258003, 103352174628, 299536839001, 7220385308804403, 7686108558349885, 10917127849295955, 724804915074540097006
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
EXAMPLE
|
51 is pentagonal and 15 is triangular
|
|
MATHEMATICA
|
dtn[L_] := Fold[10#1+#2&, 0, L] tritest[n_] := Module[{t}, t=Floor[N[Sqrt[2n]]]; 2n==t(t+1)] A={0}; For[i=1, i>0, i++, t=i(3i-1)/2; r=dtn[Reverse[IntegerDigits[t]]]; If[tritest[r]&&Mod[t, 10]>0, AppendTo[A, r]; Print[A]]]
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,more,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Description clarified and offset corrected by Lars Blomberg, May 29 2011
|
|
STATUS
|
approved
|
|
|
|