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A023712
Numbers with exactly 3 1's in their base 4 expansion.
2
21, 69, 81, 84, 86, 87, 89, 93, 101, 117, 149, 213, 261, 273, 276, 278, 279, 281, 285, 293, 309, 321, 324, 326, 327, 329, 333, 336, 338, 339, 344, 346, 347, 348, 350, 351, 353, 356, 358, 359, 361, 365, 369, 372, 374, 375, 377
OFFSET
1,1
LINKS
MATHEMATICA
Select[ Range[ 400 ], (Count[ IntegerDigits[ #, 4 ], 1 ]==3)& ]
CROSSREFS
Sequence in context: A175461 A272627 A043339 * A045124 A045100 A038471
KEYWORD
nonn,base,easy
STATUS
approved