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!)
 A034708 Numbers for which the sum of reciprocals of digits is an integer. 9
 1, 11, 22, 111, 122, 212, 221, 236, 244, 263, 326, 333, 362, 424, 442, 623, 632, 1111, 1122, 1212, 1221, 1236, 1244, 1263, 1326, 1333, 1362, 1424, 1442, 1623, 1632, 2112, 2121, 2136, 2144, 2163, 2211, 2222, 2316, 2361, 2414, 2441, 2488, 2613, 2631, 2666 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Intersection of A214957 and A052382: A214950(a(n))*A168046(a(n)) = 1. - Reinhard Zumkeller, Aug 02 2012 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 MAPLE P:=proc(n) local a; if searchtext("0", convert(n, string))=0 then a:=convert(n, base, 10); if frac(add(1/a[k], k=1..nops(a)))=0 then n; fi; fi; end: seq(P(i), i=1..2666); # Paolo P. Lava, Apr 17 2018 MATHEMATICA f[ n_ ] := 1/n a[ n_ ] := Apply[ Plus, Map[ f, IntegerDigits[ n ] ] ] Select[ Range[ 1000 ], FreeQ[ IntegerDigits[ # ], 0 ] && IntegerQ[ a [ # ] ] & ] (* Santi Spadaro, Oct 13 2001 *) Select[Range[3000], DigitCount[#, 10, 0]==0 && IntegerQ[Total[ 1/IntegerDigits[#]]]&] (* Harvey P. Dale, May 06 2012 *) PROG (Haskell) a034708 n = a034708_list !! (n-1) a034708_list = filter ((== 1) . a168046) a214957_list -- Reinhard Zumkeller, Aug 02 2012 (PARI) isok(n) = {my(d = digits(n)); vecmin(d) && denominator(sum(k=1, #d, 1/d[k])) == 1; } \\ Michel Marcus, Feb 12 2016 (Python) from fractions import Fraction def srd(n): return sum(Fraction(1, int(d)) for d in str(n)) # assumes no 0's def ok(n): return False if '0' in str(n) else srd(n).denominator == 1 def aupto(nn): return [m for m in range(1, nn+1) if ok(m)] print(aupto(2666)) # Michael S. Branicky, Jan 11 2021 CROSSREFS Cf. A052382, A168046, A214950, A214957. Sequence in context: A047902 A081930 A143964 * A091784 A213972 A061852 Adjacent sequences:  A034705 A034706 A034707 * A034709 A034710 A034711 KEYWORD nonn,base,nice AUTHOR 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 July 24 17:43 EDT 2021. Contains 346273 sequences. (Running on oeis4.)