A295017 -id:A295017 - cp's OEIS frontend

A295022 Cubes whose largest digit is 7.

27, 2744, 3375, 12167, 17576, 27000, 157464, 166375, 175616, 250047, 274625, 300763, 474552, 753571, 1157625, 1367631, 1771561, 2000376, 2352637, 2460375, 2571353, 2744000, 3176523, 3375000, 4330747, 4657463, 4741632, 5177717, 5451776, 6644672, 7645373, 11543176, 12167000

Offset: 1

M. F. Hasler, Nov 13 2017

For any term a(n), all numbers of the form a(n)*10^3k, k >= 0, are in this sequence. We could call "primitive" the terms not of this form, i.e., those without trailing '0'.

			27 is in the sequence because it is a cube, 27 = 3^3, and its largest digit is 7.

Cf. A294997 (the corresponding cube roots); A278936, A294663, A295025, A295021, A295023, A295024 (same for digit 3 .. 9); A295017 (same for squares).

Cf. A000578 (the cubes).

for(n=1,250, vecmax(digits(n^3))==7 &&print1(n^3,","))

a(n) = A294997(n)^3.

A295007 Numbers n such that the largest digit of n^2 is 7.

Original entry on oeis.org

24, 26, 42, 52, 61, 69, 74, 76, 82, 84, 85, 88, 124, 131, 132, 144, 154, 165, 166, 174, 181, 189, 194, 218, 224, 226, 234, 239, 240, 260, 265, 266, 269, 271, 274, 275, 276, 319, 326, 356, 371, 376, 384, 415, 416, 418, 419, 420, 421, 448, 455, 466, 474, 476, 520, 521, 524, 525, 526, 552

Offset: 1

M. F. Hasler, Nov 12 2017

			24 is in this sequence because 24^2 = 576 has 7 as largest digit.

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

Cf. A295017 (the corresponding squares), A277959 .. A277961 (same for digit 2 .. 4), A295005 .. A295009 (same for digit 5 .. 9).

Cf. A000290 (the squares).

filter:= proc(n) max(convert(n^2,base,10))=7 end proc:
select(filter, [$1..1000]); # Robert Israel, Feb 19 2019

select( is_A295007(n)=n&&vecmax(digits(n^2))==7 , [0..999]) \\ The "n&&" avoids an error message for n=0.

a(n) = sqrt(A295017(n)), where sqrt = A000196 or A000194 or A003059.

cp's OEIS Frontend

A295022 Cubes whose largest digit is 7.

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