A289742 Sizes of wrenches (or spanners) using imperial units.

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, 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, 16, 2, 1, 33, 16, 17, 8, 35, 16, 9, 4, 37, 16, 19, 8, 39, 16, 5, 2

Offset: 1

Author

Robert Cailliau, Jul 11 2017

Keywords

• nonn
• dumb
• fini

Comments

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.

Examples

			The fractions are 1/4, 5/16, 3/8, 7/16, 1/2, etc.
		

Crossrefs

Cf. A007879.

Programs

Mathematica

{Numerator[#],Denominator[#]}&/@NestList[#+1/16&,1/4,50]//Flatten (* Harvey P. Dale, Oct 13 2018 *)

Formula

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.

Extensions

More terms from Harvey P. Dale, Oct 13 2018

Edited by Jon E. Schoenfield, Jul 18 2021