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A036556 Integers which when multiplied by 3 have an odd number of 1's in their binary expansion (cf. A000069). 6
7, 14, 23, 27, 28, 29, 31, 39, 46, 54, 56, 57, 58, 62, 71, 78, 87, 91, 92, 93, 95, 103, 107, 108, 109, 111, 112, 113, 114, 115, 116, 117, 119, 123, 124, 125, 127, 135, 142, 151, 155, 156, 157, 159, 167, 174, 182, 184, 185, 186, 190, 199, 206, 214 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
In other words, numbers n such that 3n is odious.
Numbers n such that valuation(binomial(3n,n),2) is odd. - Benoit Cloitre, Jun 06 2004
Intersection of A000069 and A008585 (multiples of 3), divided by 3.
LINKS
FORMULA
a(n) = A180963(n)/3. - Amiram Eldar, Aug 06 2023
MATHEMATICA
Select[ Range[ 214 ], OddQ[ Plus@@IntegerDigits[ 3#, 2 ]]& ]
PROG
(PARI) for(n=1, 214, if(valuation(binomial(3*n, n), 2)%2==1, print1(n, ", "))) \\ Benoit Cloitre, Jun 06 2004
(Magma) [ n : n in [0..150] | IsOdd(&+Intseq(3*n, 2))]; // Vincenzo Librandi, Apr 13 2011
CROSSREFS
Sequence in context: A246172 A366112 A297426 * A013644 A178894 A356183
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
Definition corrected by N. J. A. Sloane, Jan 09 2007
STATUS
approved

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Last modified March 28 13:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)