A277961 Numbers n such that 4 is the largest decimal digit of n^2.

2, 12, 18, 20, 21, 32, 38, 48, 49, 102, 120, 152, 179, 180, 182, 200, 201, 210, 318, 320, 321, 332, 338, 348, 362, 380, 451, 452, 462, 480, 482, 490, 548, 549, 649, 1002, 1012, 1020, 1021, 1049, 1102, 1111, 1188, 1200, 1201, 1429, 1488, 1498, 1518, 1520

Offset: 1

Author

Colin Barker, Nov 06 2016

Keywords

• nonn
• base

Comments

The actual squares are listed in A277948. - M. F. Hasler, Nov 12 2017

Includes 2*10^n+10^m for all n <> m. - Robert Israel, Nov 13 2017

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

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

Links

• Colin Barker, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A277948, A277959, A277960.

Programs

Maple

select(n -> max(convert(n^2,base,10))=4, [$1..10000]); # Robert Israel, Nov 13 2017

PARI

L=List(); for(n=1, 10000, if(vecmax(digits(n^2))==4, listput(L, n))); Vec(L)

Formula

a(n) = sqrt(A277948(n)), where sqrt = A000196 or A000194 or A003059. - M. F. Hasler, Nov 12 2017