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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 (list; graph; refs; listen; history; text; internal format)
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

LINKS

Table of n, a(n) for n=1..38.

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

Cf. A077485, A077486.

Sequence in context: A326707 A030476 A077355 * A179334 A068864 A068854

Adjacent sequences:  A077484 A077485 A077486 * A077488 A077489 A077490

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 07 2002

EXTENSIONS

Corrected and extended by Ray Chandler, Aug 03 2003

STATUS

approved

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Last modified November 30 06:28 EST 2021. Contains 349419 sequences. (Running on oeis4.)