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A068520
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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.
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0
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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; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 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".
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LINKS
| Index entries for similar sequences
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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.
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CROSSREFS
| Sequence in context: A087346 A060314 A109303 * A171901 A033283 A044851
Adjacent sequences: A068517 A068518 A068519 * A068521 A068522 A068523
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KEYWORD
| base,nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Mar 21 2002
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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
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