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A255343 Numbers n such that there are exactly three 1's in their factorial base representation (A007623). 6
9, 27, 31, 32, 35, 39, 45, 57, 81, 105, 123, 127, 128, 131, 135, 141, 145, 146, 149, 150, 154, 157, 158, 161, 163, 164, 167, 171, 175, 176, 179, 183, 189, 195, 199, 200, 203, 207, 213, 219, 223, 224, 227, 231, 237, 249, 267, 271, 272, 275, 279, 285, 297, 321, 345, 369, 387, 391, 392, 395, 399, 405, 417, 441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..6769

EXAMPLE

The factorial base representation (A007623) of 9 is "111", which contains exactly three 1's, thus 3 is included in the sequence.

The f.b.r. of 27 is "1011", with exactly three 1's, thus 27 is included in the sequence.

The f.b.r. of 81 is "3111", with exactly three 1's, thus 81 is included in the sequence.

MATHEMATICA

factBaseIntDs[n_] := Module[{m, i, len, dList, currDigit}, i = 1; While[n > i!, i++]; m = n; len = i; dList = Table[0, {len}]; Do[currDigit = 0; While[m >= j!, m = m - j!; currDigit++]; dList[[len - j + 1]] = currDigit, {j, i, 1, -1}]; If[dList[[1]] == 0, dList = Drop[dList, 1]]; dList]; s = Table[FromDigits[factBaseIntDs[n]], {n, 480}]; Flatten@ Position[s, x_ /; DigitCount[x][[1]] == 3](* Michael De Vlieger, Apr 27 2015, after Alonso del Arte at A007623 *)

PROG

(Scheme, with Antti Karttunen's IntSeq-library)

(define A255343 (MATCHING-POS 1 0 (lambda (n) (= 3 (A257511 n)))))

CROSSREFS

Cf. A007623, A257511, A255411, A255341, A255342.

Subsequence of A256450.

Sequence in context: A115148 A022701 A276003 * A108107 A216168 A036303

Adjacent sequences:  A255340 A255341 A255342 * A255344 A255345 A255346

KEYWORD

nonn,base

AUTHOR

Antti Karttunen, Apr 27 2015

STATUS

approved

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Last modified July 20 01:17 EDT 2019. Contains 325168 sequences. (Running on oeis4.)