OFFSET
1,5
FORMULA
a(n) = # { k in A085844 | k < 2^n }. - M. F. Hasler, Feb 24 2014
EXAMPLE
a(12) = 8 because the values of k satisfying the condition for k < 2^12 are {6, 28, 411, 496, 604, 1305, 3664, 4086}. - V. Raman, Feb 18 2014
PROG
(PARI) a(n)=sum(k=1, 2^n, vecsort(digits(k)) == vecsort(digits(sigma(k)-k))) \\ Use digits(n)=eval(Vec(Str(n))) in old versions of PARI. - V. Raman, Feb 18 2014, edited by M. F. Hasler, Feb 24 2014
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
V. Raman, Sep 06 2012
STATUS
approved