login
A283104
Second differences of Stern's diatomic sequence (A002487).
1
-1, 1, -2, 3, -3, 2, -3, 5, -4, 3, -5, 6, -5, 3, -4, 7, -5, 4, -7, 9, -8, 5, -7, 10, -7, 5, -8, 9, -7, 4, -5, 9, -6, 5, -9, 12, -11, 7, -10, 15, -11, 8, -13, 15, -12, 7, -9, 14, -9, 7, -12, 15, -13, 8, -11, 15, -10, 7, -11, 12, -9, 5, -6, 11, -7, 6, -11, 15, -14, 9, -13, 20, -15, 11, -18, 21, -17, 10, -13, 21, -14, 11, -19
OFFSET
0,3
FORMULA
G.f.: -1/x + ((1 - x)^2/x)*Product_{k>=0} (1 + x^(2^k) + x^(2^(k+1))).
MATHEMATICA
Differences[a[0] = 0; a[1] = 1; a[n_] := If[EvenQ[n], a[n/2], a[(n - 1)/2] + a[(n + 1)/2]]; Table[a[n], {n, 0, 84}], 2]
CoefficientList[Series[-1/x + ((1 - x)^2/x) Product[1 + x^2^k + x^2^(k + 1), {k, 0, 20}], {x, 0, 82}], x]
CROSSREFS
Sequence in context: A242392 A002963 A046677 * A109747 A105612 A141744
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Feb 28 2017
STATUS
approved