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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 A340237 A216168 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 June 18 11:58 EDT 2021. Contains 345098 sequences. (Running on oeis4.)