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A145830 Indices for which A145768 (XOR of squares of the numbers 1...n) is a power of 2. 3
1, 7, 9, 16, 47, 63 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Next term is > 10^7.
a(7) > 1.5*10^9. [Jon E. Schoenfield, Jan 14 2009]
a(7) > 10^11. [Sean A. Irvine, Aug 12 2010]
LINKS
MATHEMATICA
Position[ FoldList[ BitXor, 0, Range[10^6]^2], n_ /; IntegerQ[Log[2, n]]] - 1 // Flatten (* Jean-François Alcover, Sep 30 2013 *)
PROG
(PARI) an=0; for( i=1, 10^6, an=bitxor(an, i^2); an & an==1<<valuation(a, 2) & print1(i", "))
CROSSREFS
A145830 = A145768 intersect A000079. A145768(a(n)) = 2^A145831(n); See also A145827-A145829.
Sequence in context: A249333 A020691 A366674 * A195563 A250292 A140364
KEYWORD
more,nice,nonn
AUTHOR
M. F. Hasler, Oct 20 2008
STATUS
approved

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Last modified March 19 06:29 EDT 2024. Contains 370953 sequences. (Running on oeis4.)