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A316561 Squarefree numbers whose arithmetic mean of digits is 4. 0
17, 26, 35, 53, 62, 71, 129, 138, 165, 174, 183, 219, 237, 246, 255, 273, 282, 291, 309, 318, 327, 345, 354, 381, 390, 417, 426, 435, 453, 462, 471, 534, 543, 561, 570, 606, 615, 633, 642, 651, 705, 714, 723, 741, 813, 822, 831, 903, 921, 930, 1069, 1087, 1159 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..53.

EXAMPLE

26 = 2*13 is a 2-digit squarefree number whose arithmetic mean of digits is (2 + 6)/2 = 4. Hence, 26 is a term.

165 = 3 * 5 * 11 is a 3-digit squarefree number whose arithmetic mean of digits is (1 + 6 + 5)/3 = 4. Hence, 165 is a term.

MAPLE

filter:= proc(n) local L;

  if not numtheory:-issqrfree(n) then return false fi;

  L:= convert(n, base, 10);

  convert(L, `+`)=4*nops(L)

end proc:

select(filter, [$1..1000]); # Robert Israel, Jul 06 2018

MATHEMATICA

Select[Range[5000], Mean[IntegerDigits[#]] == 4 && SquareFreeQ[#] &]

CROSSREFS

Intersection of A005117 (squarefree numbers) and A061387.

Cf. A316484.

Sequence in context: A212909 A273785 A171169 * A034963 A120143 A031204

Adjacent sequences:  A316558 A316559 A316560 * A316562 A316563 A316564

KEYWORD

nonn,base

AUTHOR

K. D. Bajpai, Jul 06 2018

STATUS

approved

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Last modified September 21 19:39 EDT 2019. Contains 327279 sequences. (Running on oeis4.)