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A147755
a(n) = the largest integer that, when represented in binary, occurs at least twice as a substring in the binary representation of n.
3
1, 0, 1, 1, 3, 0, 1, 2, 1, 1, 1, 3, 7, 0, 1, 2, 1, 2, 5, 2, 3, 1, 1, 2, 3, 3, 3, 7, 15, 0, 1, 2, 1, 4, 2, 2, 3, 2, 2, 10, 5, 2, 5, 3, 7, 1, 1, 2, 3, 2, 5, 6, 3, 3, 3, 3, 3, 7, 7, 15, 31, 0, 1, 2, 1, 4, 2, 2, 3, 4, 9, 2, 2, 4, 2, 3, 7, 2, 2, 2, 2, 10, 21, 5, 5, 2, 2, 5, 11, 3, 5, 7, 15, 1, 1, 2, 3, 4, 2, 6, 3, 2
OFFSET
3,5
COMMENTS
The substrings (each equal to the binary representation of a(n)) may overlap in the binary representation of n.
LINKS
EXAMPLE
21 in binary is 10101. 101 (5 in decimal) occurs twice in 10101: (101)01 and 10(101). Since no larger integer (when represented in binary) occurs more than once within 10101, then a(21) = 5.
MATHEMATICA
Table[With[{d = IntegerDigits[n, 2]}, SelectFirst[Range[n, 0, -1], SequenceCount[d, IntegerDigits[#, 2], Overlaps -> True] >= 2 &]], {n, 3, 104}] (* Michael De Vlieger, Oct 30 2017 *)
CROSSREFS
Sequence in context: A224878 A129555 A339558 * A307195 A231188 A249695
KEYWORD
base,nonn,look
AUTHOR
Leroy Quet, Nov 11 2008
EXTENSIONS
Extended by Ray Chandler, Nov 14 2008
STATUS
approved