This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A137119 Numbers k such that k and k^2 use only the digits 2, 6, 7 and 9. 0
 26, 27, 277, 269777 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Generated with DrScheme. No further terms up to 2*10^27. - Robert Israel, Oct 04 2019 LINKS J. Wellons, Tables of Shared Digits EXAMPLE 269777^2 = 72779629729. MAPLE Extend:= proc(x, d) local i;   op(select(t -> member(floor(t^2/10^(d)) mod 10, {2, 6, 7, 9}), [seq(i*10^d+x, i=[2, 6, 7, 9])])) end proc: R[0]:= {6, 7}: for m from 1 to 10 do R[m]:= map(Extend, R[m-1], m) od: {seq(op(select(t -> convert(convert(t^2, base, 10), set) subset {2, 6, 7, 9}, R[m])), m=0..10)}; # Robert Israel, Oct 04 2019 PROG (MAGMA) [k:k in [1..10^6]| Set(Intseq(k)) join Set(Intseq(k^2)) subset {2, 6, 7, 9}]; // Marius A. Burtea, Oct 04 2019 (Python) def test(n):     while n > 0:         d, n = n%10, n//10         if d == 0 or d == 1 or d == 3 or d == 4 or d == 5 or d == 8:             return 0     return 1 n, a = 0, 1 while n >= 0:     if test(a) and test(a*a):         n = n+1         print(n, a)     a = a+1 # A.H.M. Smeets, Oct 05 2019 CROSSREFS Sequence in context: A136923 A042394 A137118 * A042396 A042398 A042400 Adjacent sequences:  A137116 A137117 A137118 * A137120 A137121 A137122 KEYWORD nonn,base,more AUTHOR Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008 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 December 14 07:03 EST 2019. Contains 329978 sequences. (Running on oeis4.)