The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A241081 Numbers that are not perfect squares but that can never be ruled out as perfect squares by any final group of digits. 2
 41, 89, 129, 161, 164, 201, 209, 241, 249, 281, 321, 329, 356, 369, 401, 409, 449, 481, 489, 516, 521, 561, 569, 601, 609, 641, 644, 649, 656, 681, 689, 721, 761, 769, 801, 804, 809, 836, 849, 881, 889, 921, 929, 964, 969, 996, 1001, 1009, 1025, 1041 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All nonsquare numbers of the form 40n+1 or 40n+9 multiplied by a power of 4 times a power of 25. LINKS EXAMPLE 41 is in the sequence because there are square numbers ending in ...00041 for any number of zeros. 49 isn't in the sequence because it is a perfect square. 50 isn't in the sequence because there are no squares ending in 50. PROG (PARI) al(n) = {local(r=vector(n), x41, x49, i4=1, x4, i25=1, x25);    x41=41; x49=89; x4=4*41; x25=25*41;    for(k=1, n, r[k]=min(min(x41, x49), min(x4, x25));       if(r[k]==x41, while(issquare(x41+=40), 0));       if(r[k]==x49, while(issquare(x49+=40), 0));       if(r[k]==x4, x4=4*r[i4++]);       if(r[k]==x25, x25=25*r[i25++])); r} \\ Franklin T. Adams-Watters, Apr 18 2014 CROSSREFS Sequence in context: A242708 A282533 A199983 * A188173 A142411 A139924 Adjacent sequences:  A241078 A241079 A241080 * A241082 A241083 A241084 KEYWORD nonn,base AUTHOR J. Lowell, Apr 15 2014 EXTENSIONS More terms from Franklin T. Adams-Watters, Apr 18 2014 STATUS approved

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

Last modified August 7 19:55 EDT 2022. Contains 355994 sequences. (Running on oeis4.)