[seqfan] Re: The inverse Euler transformation of A035938

Peter Luschny peter.luschny at googlemail.com
Sun Jan 22 19:54:28 CET 2012


WK> What does EULERi do?

It amounts to (in Sage parlance):

def A035938(len) :
    L = []; M = []
    for i in range(len) :
        s = sum(d*[1, 0, 1, 1, 0, 1, 0][(d-1) % 7] for d in divisors(i+1))
        L.append(s)
        s = s + sum(L[d-1]*M[i-d] for d in (1..i))
        M.append(s/(i+1))
    return M

A035938(20)
[1, 1, 2, 3, 3, 5, 6, 8, 10, 13, 16, 21, 25, 31, 38, 47, 56, 69, 82, 99]

Peter



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