

A007379


Earliest sequence with a(a(n)) = 4n.
(Formerly M0973)


10



0, 2, 4, 5, 8, 12, 7, 24, 16, 10, 36, 13, 20, 44, 15, 56, 32, 18, 68, 21, 48, 76, 23, 88, 28, 26, 100, 29, 96, 108, 31, 120, 64, 34, 132, 37, 40, 140, 39, 152, 144, 42, 164, 45, 52, 172, 47, 184, 80, 50, 196, 53, 176, 204, 55, 216, 60, 58, 228, 61, 224, 236, 63, 248
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,2


REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000
Index entries for sequences of the a(a(n)) = 2n family


FORMULA

a(8n)=4*a(2n), a(8n+1)=8n+2, a(8n+2)=32n+4, a(8n+3)=8n+5, a(8n+4)=4*a(2n+1), a(8n+5)=32n+12, a(8n+6)=8n+7, a(8n+7)=32n+24


MATHEMATICA

a[n_] := a[n] = Which[ Mod[n, 8] == 0, 4*a[n/4], Mod[n, 8] == 1, n+1, Mod[n, 8] == 2, 4*(n2)+4, Mod[n, 8] == 3, n+2, Mod[n, 8] == 4, 4*a[(n4)/4+1], Mod[n, 8] == 5, 4*(n5) + 12, Mod[n, 8] == 6, n+1, True, 4*(n7)+24]; a[0] = 0; Table[ a[n], {n, 0, 63}] (* JeanFrançois Alcover, Sep 24 2012 *)


CROSSREFS

Cf. A002516, A002517.
Sequence in context: A280017 A080136 A080033 * A080588 A032850 A190190
Adjacent sequences: A007376 A007377 A007378 * A007380 A007381 A007382


KEYWORD

nonn,nice


AUTHOR

Colin Mallows, N. J. A. Sloane, Mira Bernstein


EXTENSIONS

Formula and more terms from Henry Bottomley, Apr 27 2000


STATUS

approved



