A037884 a(n)=(1/2)*Sum{|d(i)-e(i)|} where Sum{d(i)*7^i} is the base 7 representation of n and e(i) are the digits d(i) in nondecreasing order.
0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 0, 0, 0, 1, 2, 3, 4, 0, 0, 0, 0, 1, 2, 3, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 0, 0, 1, 2, 3, 4, 5, 1, 1, 1, 2, 3, 4, 5, 2, 2, 2, 2, 3, 4, 5, 3, 3, 3, 3, 3, 4, 5, 4, 4, 4, 4, 4, 4, 5
Offset: 1
Programs
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Maple
A037884 := proc(n) local a,dgs,dgsE ; a := 0 ; dgs := convert(n,base,7); dgsE := sort(dgs) ; for i from 1 to nops(dgs) do a := a+ abs(op(i,dgs)-op(i,dgsE)) ; end do: a/2 ; end proc: # R. J. Mathar, Oct 19 2015
Extensions
Definition swapped with A037875. - R. J. Mathar, Oct 19 2015