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 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
 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; text; internal format)
 OFFSET 1,1 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". LINKS 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: A337240 A109303 A338214 * A171901 A033283 A044851 Adjacent sequences:  A068517 A068518 A068519 * A068521 A068522 A068523 KEYWORD base,nonn AUTHOR Joseph L. Pe, Mar 21 2002 EXTENSIONS More terms from Larry Reeves (larryr(AT)acm.org), Jun 21 2002 Edited by Klaus Brockhaus, Jul 02 2003 STATUS approved

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Last modified April 11 00:03 EDT 2021. Contains 342877 sequences. (Running on oeis4.)