login
A119073
Triangular numbers composed of digits {0,4,6}.
2
6, 66, 406, 666, 66066, 446040, 600060, 46046406, 440466040, 4040600460, 6604444400406, 4440066066400004040, 644006046066000066046, 44464646466606404046664666, 464440406444064040044646006604604066, 660466006640066446666000606004066646, 60404640400640406040004460664400044060
OFFSET
1,1
FORMULA
a(n) = A000217(A119074(n)). - Tyler Busby, Mar 27 2023
MATHEMATICA
Rest[Select[FromDigits/@Tuples[{0, 4, 6}, 10], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *)
PROG
(Magma) [t: n in [1..2*10^7] | Set(Intseq(t)) subset {0, 4, 6} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015
CROSSREFS
See A119033 for a table of cross-references.
Sequence in context: A175455 A185253 A192089 * A028559 A249639 A163699
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(15)-a(16) from Max Alekseyev, May 10 2009
a(17) from Tyler Busby, Mar 27 2023
STATUS
approved