A062118 Numbers k such that k^2 has k as its middle digits.

1, 50, 60, 250, 3792, 7600, 376000, 495475, 625000, 971582, 66952741, 93760000, 177656344, 3199268655, 9062500000, 10937600000, 788138178328, 860628177919, 890625000000, 2291665833333, 2780225311054, 2890625000000, 71093760000000, 128906250000000

Offset

1,2

Comments

Some of the terms are automorphic numbers (A003226) multiplied by an appropriate power of 10. a(25) > 10^15. - Giovanni Resta, Jul 29 2013

References

Computed by Robert Israel.

Links

Table of n, a(n) for n=1..24.

Example

a(5)=3792 because 3792^2 = 14379264 has 3792 as its middle digits.

Mathematica

Do[ If[ StringPosition[ ToString[n^2], ToString[n]] [[1, 1]] == (Ceiling[ Log[10, n^2] ] - Ceiling[ Log[10, n] ])/2 + 1, Print[n] ], {n, 1, 10^9} ]

Crossrefs

k^2 is given in A062120.

Sequence in context: A046832 A046834 A046836 * A167329 A179796 A215468

Adjacent sequences: A062115 A062116 A062117 * A062119 A062120 A062121

Keyword

nonn,base,nice

Author

Brian Wallace (wallacebrianedward(AT)yahoo.co.uk), Jun 28 2001

Extensions

Corrected and extended by Robert G. Wilson v, Aug 08 2001

a(15)-a(24) from Giovanni Resta, Jul 29 2013

Status

approved