login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A117960 Triangular numbers with only odd digits. 2
1, 3, 15, 55, 91, 153, 171, 351, 595, 1711, 1953, 5151, 5995, 9591, 11175, 11935, 15753, 15931, 17391, 17955, 31375, 33153, 35511, 73153, 153735, 171991, 173755, 193131, 193753, 371953, 399171, 513591, 551775, 559153, 571915, 791911, 917335, 939135, 1335795 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..1000

MAPLE

b:= proc(n) option remember; local k; for k from

      1+`if`(n=1, 0, b(n-1)) while 0=mul(irem(i, 2),

      i=convert(k*(k+1)/2, base, 10) ) do od; k

    end:

a:= n-> (t-> t*(t+1)/2)(b(n)):

seq(a(n), n=1..50);  # Alois P. Heinz, Jul 12 2015

CROSSREFS

Cf. A000217, A117978.

Sequence in context: A026696 A082708 A093925 * A176288 A119113 A286185

Adjacent sequences:  A117957 A117958 A117959 * A117961 A117962 A117963

KEYWORD

base,nonn

AUTHOR

Luc Stevens (lms022(AT)yahoo.com), May 03 2006

EXTENSIONS

Some terms corrected by Alois P. Heinz, Jul 12 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 20 08:39 EDT 2019. Contains 322306 sequences. (Running on oeis4.)