A058425 Numbers k such that k^2 contains only digits {0,2,5}, not ending with zero.

5, 15, 45, 235, 505, 745, 1415, 1485, 4495, 5005, 15985, 50005, 72495, 469255, 500005, 500505, 1597505, 1598515, 4474955, 5000005, 5000505, 5050005, 7085235, 15008515, 44949995, 50000005, 50000505, 50005005, 50500005, 500000005, 500000505

Offset

1,1

Comments

Most terms have a special pattern in that they have only digits 0 and 5 and could be written as Sum_{h=0..t} 5*10^f(h), where 2f(h), 2f(h)-1, and f(h1) + f(h2) are all distinct and f(0)=0 for the nonzero ending constraint. - Zhao Hui Du, Mar 12 2024

Links

Zhao Hui Du, Table of n, a(n) for n = 1..5913

Patrick De Geest, Index to related sequences.

Hisanori Mishima, Sporadic tridigital solutions.

Crossrefs

Cf. A058426.

Sequence in context: A035069 A176611 A001869 * A079798 A344814 A037504

Adjacent sequences: A058422 A058423 A058424 * A058426 A058427 A058428

Keyword

nonn,base

Author

Patrick De Geest, Nov 15 2000

Extensions

a(29)=50500005 inserted by Georg Fischer, Jan 12 2022

Status

approved