OFFSET
1,2
COMMENTS
a(n) is a multiple of 3.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..200
MATHEMATICA
With[{nn=20}, FromDigits[Flatten[IntegerDigits[#]]]&/@(Reverse/@ TakeList[ Range[0, (nn(nn+1))/2], Range[nn]])] (* Requires Mathematica version 11 or later *) (* Harvey P. Dale, Jun 10 2019 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Mar 11 2003
EXTENSIONS
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003
STATUS
approved