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A047405
Numbers that are congruent to {0, 1, 2, 3, 6} mod 8.
1
0, 1, 2, 3, 6, 8, 9, 10, 11, 14, 16, 17, 18, 19, 22, 24, 25, 26, 27, 30, 32, 33, 34, 35, 38, 40, 41, 42, 43, 46, 48, 49, 50, 51, 54, 56, 57, 58, 59, 62, 64, 65, 66, 67, 70, 72, 73, 74, 75, 78, 80, 81, 82, 83, 86, 88, 89
OFFSET
1,3
COMMENTS
For n >= 2, 5*(a(n)+k)*Pi; where k = 0, 4, 3, 1 if n mod 5 = 0 or 1, 2, 3, 4 respectively; is also the total length of irregular spiral (center points: 1, 4, 3, 2, 5) after (n-1) rotations. - Kival Ngaokrajang, Jan 08 2014
FORMULA
G.f.: x^2*(2*x^2 - x + 1)*(1+x)^2 / ( (x^4 + x^3 + x^2 + x + 1)*(x-1)^2 ). - R. J. Mathar, Dec 05 2011
CROSSREFS
Sequence in context: A139371 A335962 A079338 * A175904 A084090 A353988
KEYWORD
nonn
STATUS
approved