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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A249896 a(n+1) is next smallest square not divisible by 10 beginning with a(n), initial term is 6. 5
6, 64, 64009, 6400960036, 640096003602877347904, 640096003602877347904912233550482787380625, 6400960036028773479049122335504827873806251020537411455326101704116338781035920283225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(11) has 1374 digits, a(12) has 2749, a(13) has 5499, a(14) has 10998. - Robert Israel, Nov 25 2020

LINKS

Robert Israel, Table of n, a(n) for n = 1..10

Robert Israel, Table of n, a(n) for n = 1..14

MAPLE

R:= 6: x:= 6: s:= 2:

for iter from 1 while length(x) < 1000 do

  for d from 1 do

   if d::even then sp:= 1+ 10^(d/2)*s

   else

     sp:= ceil(sqrt(10^d*x));

     if sp mod 10 = 0 then sp:=sp+1; fi

   fi;

   if sp^2 < (x+1)*10^d then

     x:= sp^2; s:= sp; R:= R, x; break

   fi

  od;

od:

R; # Robert Israel, Nov 25 2020

PROG

(PARI) a(n)=k=n; s=1; while(s<5*10^7, if(s%10, if(s^2\(10^(#Str(s^2)-#Str(k)))==k, print1(s^2, ", "); k=s^2)); s++)

a(7)

(Python)

def f(x):

..print(x, end=', ')

..n = x

..s = 1

..while s < 10**7:

....if s % 10:

......S = str(s**2)

......if S.startswith(str(n)):

........print(s**2, end=', ')

........n = s**2

....s += 1

f(7)

CROSSREFS

Cf. A048559, A048561.

Sequence in context: A249592 A333983 A087488 * A249828 A179879 A297516

Adjacent sequences:  A249893 A249894 A249895 * A249897 A249898 A249899

KEYWORD

nonn,base,changed

AUTHOR

Derek Orr, Nov 08 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 30 02:42 EST 2020. Contains 338781 sequences. (Running on oeis4.)