|
Search: id:A094609
|
|
|
| A094609 |
|
Numbers n such that n concatenated with n+1 is triangular. |
|
+0
1
|
|
| 4, 7, 49, 52, 295, 369, 415, 499, 502, 594, 652, 760, 2254, 4999, 5002, 8827, 10330, 14877, 49999, 50002, 490150, 499999, 500002, 509949, 3347109, 4999999, 5000002, 6983470, 24913494, 49999999, 50000002
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Numbers 4, 49, 499, 4999, ...; 52, 502, 5002, 50002, ...; 594, 509949, 500999499, 500099994999, ...; 415, 490150, 499001500, 499900015000, ...; with obvious patterns are members of the sequence. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jun 09 2004
|
|
EXAMPLE
|
E.g. 5253 is triangular so 52 is a member.
|
|
MATHEMATICA
|
triQ[n_] := Block[{k = Floor[ Sqrt[2n]]}, If[ k(k + 1) == 2n, True, False]]; Do[ If[ triQ[ FromDigits[ Join[ IntegerDigits[n], IntegerDigits[n + 1]] ]] == True, Print[ n]], {n, 45000000}] (from Robert G. Wilson v Jun 09 2004)
|
|
CROSSREFS
|
Cf. A000217.
Adjacent sequences: A094606 A094607 A094608 this_sequence A094610 A094611 A094612
Sequence in context: A093102 A139030 A115439 this_sequence A049191 A013467 A060413
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Jason Earls (jcearls(AT)cableone.net), Jun 06 2004
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 09 2004
|
|
|
Search completed in 0.002 seconds
|
