[seqfan] Re: Concatenation

Robert Israel israel at math.ubc.ca
Fri Apr 23 18:06:40 CEST 2010

For concatenating a sequence of digits d1, d2, ..., dn into an integer, 
Maple can use


Robert Israel                                israel at math.ubc.ca
Department of Mathematics        http://www.math.ubc.ca/~israel 
University of British Columbia            Vancouver, BC, Canada

On Fri, 23 Apr 2010, Charles Greathouse wrote:

> How should concatenation be represented in the OEIS?
> Giovanni Resta uses // for concatenation, as in A115429.
> Leroy Quet uses U for concatenation, as in A165784.
> Farideh Firoozbakht uses . for concatenation, as in A115437.
> Patrick De Geest uses 'foo followed by bar' (with the quotes), as in
> A034821; but see also A032711.
> Amarnath Murthy denotes concatenation by concatenation, as in A089710.
> Of course there's no reason that we need to have a symbolic form, but
> these examples show that the need for some symbolic representation has
> come up many times.  I have no strong preference except to
> standardize, whether on a particular form (these or a novel one) or to
> use no such representation.
> There's not much guidance from the popular programs, which use verbose forms:
> Pari uses eval(Str(a1, ..., an)).  Mathematica uses
> FromDigits[Join[IntegerDigits[a1], ..., IntegerDigits[an]]] or
> ToExpression[StringJoin[ToString[a1], ..., ToString[an]]]. It looks
> like Maple must use (and the others could use) multiplication by an
> appropriate power of 10 and addition.
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
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