|
Search: id:A068520
|
|
|
| A068520 |
|
Numbers n which can be transformed into a true arithmetic statement by inserting zero or more parentheses and elementary arithmetic operators ((, ), +, -, *, /) and one equality sign (=) as the rightmost insertion into the decimal representation of n. |
|
+0
1
|
|
| 11, 22, 33, 44, 55, 66, 77, 88, 99, 100, 101, 110, 111, 112, 122, 123, 133, 134, 144, 145, 155, 156, 166, 167, 177, 178, 188, 189, 199, 200, 202, 212, 213, 220, 221, 224, 235, 236, 246, 248, 257, 268, 279, 300, 303, 312, 313, 314, 321, 325, 326, 330, 331
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
The minus sign is considered only as two-place infix operator, not as one-place prefix operator. Therefore -1 + 2 = 1 is not allowed and 121 is not a term.
For obvious reasons these numbers are called (elementary) "didactic numbers".
|
|
LINKS
|
Index entries for similar sequences
|
|
EXAMPLE
|
7 = 7; 1 * 0 = 0; 2 - 2 = 0; 2 / 2 = 1; 18 / 2 = 9; 2 * (3 + 4) = 14. Therefore 77, 100, 220, 221, 1829 and 23414 are terms of the sequence.
|
|
CROSSREFS
|
Sequence in context: A087346 A060314 A109303 this_sequence A033283 A044851 A160861
Adjacent sequences: A068517 A068518 A068519 this_sequence A068521 A068522 A068523
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Mar 21 2002
|
|
EXTENSIONS
|
More terms from Larry Reeves (larryr(AT)acm.org), Jun 21 2002
Edited by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 02 2003
|
|
|
Search completed in 0.002 seconds
|
