A046834 Internal digits of n^2 include digits of n as subsequence.

50, 60, 250, 500, 600, 760, 1050, 2050, 2500, 3050, 3628, 3710, 3760, 3792, 4050, 4410, 5000, 5010, 5050, 5060, 5250, 6000, 6010, 6050, 6250, 6760, 7050, 7560, 7600, 8050, 8250, 8260, 8882, 9050, 9460, 10050, 10500, 14650, 14651, 20050, 20500

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base
• easy

Comments

If n is a member then so is 10*n. - Robert Israel, May 07 2020

Examples

			a(7) = 1050 is a term because 1050^2 = 1102500; remove the first and last to get internal digits 10250, and 1050 is a subsequence of 10250. - _Robert Israel_, May 07 2020
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000 (first 5000 terms from Robert Israel)

Crossrefs

Cf. A046831, A052212.

Programs

Maple

filter:= n -> StringTools:-IsSubSequence(sprintf("%d",n),sprintf("%d",n^2)[2..-2]):
select(filter, [$10..30000]); # Robert Israel, May 07 2020

Python

from itertools import count, islice
def A046834_gen(startvalue=1): # generator of terms >= startvalue
    for k in count(max(startvalue,1)):
        c = iter(str(k**2)[1:-1])
        if all(map(lambda b:any(map(lambda a:a==b,c)),str(k))):
            yield k
A046834_list = list(islice(A046834_gen(),20)) # Chai Wah Wu, Apr 03 2023