

A092734


Numbers n occurring in binary representation of n*(n+1)/2.


1



1, 3, 7, 13, 15, 20, 31, 63, 72, 82, 109, 127, 141, 177, 243, 255, 272, 511, 693, 886, 1023, 1056, 1311, 1350, 1480, 2047, 2130, 2378, 3812, 4039, 4095, 4160, 4982, 5422, 5546, 6906, 6933, 7365, 7956, 8191, 9418, 11531, 12465, 13069, 13713
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OFFSET

1,2


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..100
Index entries for sequences related to binary expansion of n


EXAMPLE

n=13>'1101', 13*(13+1)/2=91>'1011011': '..1101.', therefore 13 is a term.


MATHEMATICA

Select[Range[15000], SequenceCount[IntegerDigits[(#(#+1))/2, 2], IntegerDigits[ #, 2]]>0&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 20 2019 *)


CROSSREFS

Cf. A007088, A000217.
Sequence in context: A310252 A056530 A310253 * A209839 A192854 A002236
Adjacent sequences: A092731 A092732 A092733 * A092735 A092736 A092737


KEYWORD

nonn


AUTHOR

Reinhard Zumkeller, Apr 12 2004


STATUS

approved



