

A257848


a(n) = floor(n/8) * (n mod 8).


1



0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 0, 2, 4, 6, 8, 10, 12, 14, 0, 3, 6, 9, 12, 15, 18, 21, 0, 4, 8, 12, 16, 20, 24, 28, 0, 5, 10, 15, 20, 25, 30, 35, 0, 6, 12, 18, 24, 30, 36, 42, 0, 7, 14, 21, 28, 35, 42, 49, 0, 8, 16, 24, 32, 40, 48, 56, 0, 9
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OFFSET

0,11


COMMENTS

Equivalently, write n in base 8, multiply the last digit by the number with its last digit removed.


LINKS

Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,1).


FORMULA

a(n) = 2*a(n8)a(n16).  Colin Barker, May 11 2015
G.f.: x^9*(7*x^6+6*x^5+5*x^4+4*x^3+3*x^2+2*x+1) / ((x1)^2*(x+1)^2*(x^2+1)^2*(x^4+1)^2).  Colin Barker, May 11 2015


PROG

(PARI) a(n, b=8)=(n=divrem(n, b))[1]*n[2]
(PARI) concat([0, 0, 0, 0, 0, 0, 0, 0, 0], Vec(x^9*(7*x^6+6*x^5+5*x^4+4*x^3+3*x^2+2*x+1) / ((x1)^2*(x+1)^2*(x^2+1)^2*(x^4+1)^2) + O(x^100))) \\ Colin Barker, May 11 2015


CROSSREFS

Cf. A142150 (the base 2 analog), A115273, A257844  A257850.
Sequence in context: A037886 A031045 A010877 * A195831 A265521 A004183
Adjacent sequences: A257845 A257846 A257847 * A257849 A257850 A257851


KEYWORD

nonn,base,easy


AUTHOR

M. F. Hasler, May 10 2015


STATUS

approved



