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A291629 Numbers k such that 4 is the smallest decimal digit of k^2. 7
2, 7, 8, 22, 28, 67, 74, 88, 92, 93, 212, 214, 216, 234, 238, 242, 258, 262, 293, 308, 667, 676, 678, 683, 684, 692, 707, 738, 758, 772, 817, 822, 828, 863, 864, 866, 886, 888, 892, 893, 926, 938, 972, 974, 978, 2113, 2114, 2116, 2133, 2137, 2158, 2163, 2167 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

First digit can't be 1, 4 or 5; last digit can't be 0, 1 or 9. - Robert Israel, Mar 25 2020

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

28 is in the sequence because 28^2 = 784, the smallest decimal digit of which is 4.

MAPLE

filter:= n -> min(convert(n^2, base, 10))=4:

select(filter, [$1..10000]); # Robert Israel, Mar 25 2020

MATHEMATICA

Select[Range[2500], Min[IntegerDigits[#^2]]==4&] (* Harvey P. Dale, Aug 03 2019 *)

PROG

(PARI) select(k->vecmin(digits(k^2))==4, vector(3000, k, k))

CROSSREFS

Cf. A291625, A291626, A291627, A291628, A291630, A291631.

Sequence in context: A167767 A054601 A279847 * A117558 A117559 A236291

Adjacent sequences: A291626 A291627 A291628 * A291630 A291631 A291632

KEYWORD

nonn,base

AUTHOR

Colin Barker, Aug 28 2017

STATUS

approved

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Last modified December 7 17:25 EST 2022. Contains 358668 sequences. (Running on oeis4.)