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%I #20 Jul 20 2021 03:37:44
%S 1,4,5,16,3,8,7,16,1,2,9,16,5,8,11,16,3,4,13,16,7,8,15,16,1,1,17,16,9,
%T 8,19,16,5,4,21,16,11,8,23,16,3,2,25,16,13,8,27,16,7,4,29,16,15,8,31,
%U 16,2,1,33,16,17,8,35,16,9,4,37,16,19,8,39,16,5,2
%N Sizes of wrenches (or spanners) using imperial units.
%C Found on sets of wrenches (US) or spanners (UK) for nut sizes in imperial units. List gives pairs (numerator, denominator) for the reduced fractions that specify the sizes.
%F The sizes, which come in integer multiples of 1/16 inch, are equal to 4/16", 5/16", 6/16", ... but as it is customary to reduce fractions, these sizes are embossed on the wrenches as 1/4, 5/16, 3/8, .... This reduction leads to a set of numbers that are not as simple as those on metric wrenches (where the sequence is simply 6mm, 7mm, 8mm, 9mm, ...) and can make it more difficult to find the next larger or smaller wrench if the current one does not fit. So far nobody has ever been able to find the next number when I give the first 7 terms. It is similar in fun value to the clock chiming sequence A007879.
%e The fractions are 1/4, 5/16, 3/8, 7/16, 1/2, etc.
%t {Numerator[#],Denominator[#]}&/@NestList[#+1/16&,1/4,50]//Flatten (* _Harvey P. Dale_, Oct 13 2018 *)
%Y Cf. A007879.
%K nonn,dumb,fini
%O 1,2
%A _Robert Cailliau_, Jul 11 2017
%E More terms from _Harvey P. Dale_, Oct 13 2018
%E Edited by _Jon E. Schoenfield_, Jul 18 2021