login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A095902
Number of odd entries in A004001 that are <= 2^n.
3
1, 2, 2, 3, 6, 12, 27, 55, 115, 235, 490, 994, 2008, 4036, 8120, 16280, 32640, 65344, 130879, 261935, 524057, 1048301, 2096855, 4193951, 8388239, 16776799, 33554339, 67109539, 134220995
OFFSET
0,2
COMMENTS
Even entries and odd entries are equal only when n=4, 6 and 12. Past that, the evens outnumber the odds.
FORMULA
a(n) = A283480(2^n) - Antti Karttunen, Mar 21 2017
MATHEMATICA
a[1] = a[2] = 1; a[n_] := a[n] = a[a[n - 1]] + a[n - a[n - 1]]; c = 0; k = 1; Do[ While[k <= 2^n, If[ Mod[ a[k], 2] == 1, c++ ]; k++ ]; Print[c], {n, 21}]
PROG
(Scheme) (define (A095902 n) (A283480 (A000079 n))) ;; Antti Karttunen, Mar 21 2017
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jun 12 2004
EXTENSIONS
a(22)-a(28) from Donovan Johnson, Jan 28 2009
STATUS
approved