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A089999 Smallest triangular number with Hamming weight n (i.e. with exactly n 1's when written in binary). 3
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 (list; graph; refs; listen; history; internal format)
OFFSET

1,3

COMMENTS

A000120(a(n)) = n.

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 (from Robert G. Wilson v Dec 03 2003)

CROSSREFS

Cf. A000217, A089998, A061712, A090002.

Sequence in context: A024011 A052445 A188721 * A124397 A043081 A091675

Adjacent sequences:  A089996 A089997 A089998 * A090000 A090001 A090002

KEYWORD

nonn,base

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 20 2003

EXTENSIONS

More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 03 2003

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Last modified February 15 14:57 EST 2012. Contains 205823 sequences.