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A089999
Smallest triangular number with Hamming weight n (i.e., with exactly n 1's when written in binary).
9
0, 1, 3, 21, 15, 55, 190, 253, 703, 3003, 5886, 13695, 4095, 49141, 106491, 192510, 784378, 1915903, 3407355, 5240703, 15986685, 30400503, 48201471, 124780503, 247431135, 602930175, 1608777726, 4290575295, 7482375615, 15938355070
OFFSET
0,3
COMMENTS
A000120(a(n)) = n.
a(n) = A000217(A211201(n)). - Reinhard Zumkeller, Mar 18 2013
LINKS
MATHEMATICA
a = Table[0, {30}]; Do[t = n(n + 1)/2; c = Count[ IntegerDigits[t, 2], 1]; If[ a[[c + 1]] == 0, a[[c + 1]] = t], {n, 1, 10^8}]; a (* Robert G. Wilson v, Dec 03 2003 *)
PROG
(Haskell)
a089999 = a000217 . a211201 -- Reinhard Zumkeller, Mar 18 2013
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Nov 20 2003
EXTENSIONS
More terms from Robert G. Wilson v, Dec 03 2003
Offset corrected by Donovan Johnson, May 01 2012
STATUS
approved