The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A212223 a(n) is the least integer greater than 1 whose expansion in prime bases 2 to prime(n) have equal sum of digits. 1
 2, 6, 6, 882, 1386, 2007986541 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Case a(1) is trivial since only base prime(1)=2 is involved. Conjecture: the sequence never terminates. a(7) > 2.3*10^16, if it exists. - Giovanni Resta, Oct 29 2018 LINKS EXAMPLE a(5) = 1386 because that number has the same sum of digits in the first 5 prime bases 2, 3, 5, 7, 11 (see A212222 and A000040). MATHEMATICA f[n_] := Block[{p = Prime@ Range@ n, k = 2}, While[ Length[ Union[ Total@# & /@ IntegerDigits[k, p]]] != 1, k++]; k] (* Robert G. Wilson v, Oct 24 2014 *) CROSSREFS Cf. A212222, A135127, A135121, A037301. Cf. A000040. Sequence in context: A130726 A279841 A219195 * A158915 A257478 A243523 Adjacent sequences:  A212220 A212221 A212222 * A212224 A212225 A212226 KEYWORD nonn,base,hard,more AUTHOR Stanislav Sykora, May 10 2012 EXTENSIONS Name edited by Michel Marcus, Sep 14 2020 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 15 13:44 EDT 2021. Contains 343920 sequences. (Running on oeis4.)