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A077487
Squares which leave a square at every step if most significant digit and least significant digit are deleted until a one-digit or two-digit square is obtained.
0
1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 144, 196, 400, 441, 841, 900, 1369, 3364, 4096, 5041, 8649, 10000, 10816, 11449, 20164, 38416, 40000, 61009, 64009, 90000, 1000000, 1004004, 3013696, 3108169, 4000000, 4004001, 9000000, 100000000
OFFSET
1,2
COMMENTS
Sequence is infinite with nontrivial terms (10^(2k+1)+2)^2 and (2*10^(2k+1)+1)^2. - Ray Chandler, Aug 03 2003
EXAMPLE
38416 is a member as 38416, 841 and 4 all are squares.
PROG
(PARI) l=listcreate(1000); for(n=0, 9, listput(l, n^2)); for(k=3, 50, for(d1=1, 9, for(n=1, length(l), for(d2=0, 9, t1=l[n]; if(t1<10^(k-2), c=d1*10^(k-1) + t1*10 + d2; if(issquare(c), listput(l, c); ); ); ); ); ); ); l
CROSSREFS
Sequence in context: A352618 A030476 A077355 * A179334 A068867 A068864
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 07 2002
EXTENSIONS
Corrected and extended by Ray Chandler, Aug 03 2003
STATUS
approved