|
%I #11 Feb 21 2024 16:38:00
%S 11,22,33,44,55,66,77,88,99,100,101,110,111,112,122,123,133,134,144,
%T 145,155,156,166,167,177,178,188,189,199,200,202,211,212,213,220,221,
%U 224,235,236,246,248,257,268,279,300,303,312,313,314,321,325,326,330,331
%N 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.
%C 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.
%C These numbers are called (elementary) "didactic numbers".
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a068/A068520.java">Java program</a> (github)
%H <a href="/index/Fo#4x4">Index entries for similar sequences</a>
%e 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.
%e 2 - 1 = 1, therefore 211 is a term of the sequence. - _Sean A. Irvine_, Feb 21 2024
%K base,nonn
%O 1,1
%A _Joseph L. Pe_, Mar 21 2002
%E More terms from Larry Reeves (larryr(AT)acm.org), Jun 21 2002
%E Edited by _Klaus Brockhaus_, Jul 02 2003
%E Missing 211 inserted by _Sean A. Irvine_, Feb 21 2024
|
