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A077485 a(1) = 1, then smallest n-digit square which leaves a square at every step if most significant digit and least significant digit are deleted until a one-or two-digit digit square is obtained. a(2n) = 0 if no such square exists. a(2n+1) = 10^2n only if no nontrivial candidate exists. 2
1, 16, 144, 1369, 10816, 0, 1004004, 0, 100000000, 0, 10000400004, 0, 1000000000000, 0, 100000040000004, 0, 10000000000000000, 0, 1000000004000000004, 0, 100000000000000000000, 0, 10000000000400000000004 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..23.

FORMULA

Beginning with term a(6) the following pattern applies: a(4k)=0; a(4k+1)=10^4k=(10^2k)^2; a(4k+2)=0; a(4k+3)=(10^(2k+1)+2)^2. - Ray Chandler, Aug 03 2003

EXAMPLE

a(3) = 144 as 144 and 4 are both squares.

a(4) = 1369 as 1369 and 36 are both squares.

CROSSREFS

Cf. A077486.

Sequence in context: A282524 A287168 A155663 * A131705 A203538 A076029

Adjacent sequences:  A077482 A077483 A077484 * A077486 A077487 A077488

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 December 3 21:17 EST 2021. Contains 349468 sequences. (Running on oeis4.)