A092734 Numbers n occurring in binary representation of n*(n+1)/2.

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

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: A056530 A341447 A310253 * A209839 A192854 A002236

Adjacent sequences: A092731 A092732 A092733 * A092735 A092736 A092737

Keyword

nonn

Author

Reinhard Zumkeller, Apr 12 2004

Status

approved