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%I #20 Nov 13 2017 22:01:32
%S 2,12,18,20,21,32,38,48,49,102,120,152,179,180,182,200,201,210,318,
%T 320,321,332,338,348,362,380,451,452,462,480,482,490,548,549,649,1002,
%U 1012,1020,1021,1049,1102,1111,1188,1200,1201,1429,1488,1498,1518,1520
%N Numbers n such that 4 is the largest decimal digit of n^2.
%C The actual squares are listed in A277948. - _M. F. Hasler_, Nov 12 2017
%C Includes 2*10^n+10^m for all n <> m. - _Robert Israel_, Nov 13 2017
%C For any term of q digits, the first m digits don't exceed (2 * 10^m - 2) / 3 = 666..66 (m 6's) for 1 <= m <= q. - _David A. Corneth_, Nov 13 2017
%C A term a(n) is in the sequence if and only if a(n)*10^k is in the sequence, for all k >= 0. If a(n) = (x*10^k + y)*10^m with 2xy < 10^k, then (y*10^k+x)*10^m' is also in the sequence, for all m'. - _M. F. Hasler_, Nov 13 2017
%H Colin Barker, <a href="/A277961/b277961.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = sqrt(A277948(n)), where sqrt = A000196 or A000194 or A003059. - _M. F. Hasler_, Nov 12 2017
%p select(n -> max(convert(n^2,base,10))=4, [$1..10000]); # _Robert Israel_, Nov 13 2017
%o (PARI) L=List(); for(n=1, 10000, if(vecmax(digits(n^2))==4, listput(L, n))); Vec(L)
%Y Cf. A277948, A277959, A277960.
%K nonn,base
%O 1,1
%A _Colin Barker_, Nov 06 2016
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