A291629 - OEIS

%I #10 Mar 25 2020 06:54:39

%S 2,7,8,22,28,67,74,88,92,93,212,214,216,234,238,242,258,262,293,308,

%T 667,676,678,683,684,692,707,738,758,772,817,822,828,863,864,866,886,

%U 888,892,893,926,938,972,974,978,2113,2114,2116,2133,2137,2158,2163,2167

%N Numbers k such that 4 is the smallest decimal digit of k^2.

%C First digit can't be 1, 4 or 5; last digit can't be 0, 1 or 9. - _Robert Israel_, Mar 25 2020

%H Robert Israel, <a href="/A291629/b291629.txt">Table of n, a(n) for n = 1..10000</a>

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

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

%p select(filter, [$1..10000]); # _Robert Israel_, Mar 25 2020

%t Select[Range[2500],Min[IntegerDigits[#^2]]==4&] (* _Harvey P. Dale_, Aug 03 2019 *)

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

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

%K nonn,base

%O 1,1

%A _Colin Barker_, Aug 28 2017