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A069502
a(1) = 1; a(n) = smallest multiple of a(n-1) which is a palindromic triangular number.
1
1, 3, 6, 66, 8778, 6172882716
OFFSET
0,2
COMMENTS
a(7) must be larger than 5*10^41. - Patrick De Geest
MATHEMATICA
smpt[n_]:=Module[{k=2}, While[!PalindromeQ[k*n]||!OddQ[Sqrt[1+8*k*n]], k++]; k*n]; NestList[smpt, 1, 5] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 01 2019 *)
CROSSREFS
Cf. A069501.
Sequence in context: A068665 A229236 A050722 * A296374 A362822 A205081
KEYWORD
nonn,base,hard
AUTHOR
Amarnath Murthy, Mar 30 2002
EXTENSIONS
a(6) from Patrick De Geest, Jun 11 2003
STATUS
approved