A169669 - OEIS

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A169669

(first digit of n) * (last digit of n) in decimal representation.

0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 0

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

COMMENTS

a(n) = A000030(n)*A010879(n);

a(n) = A115300(n) for n<=100, A115300(101) = 0;

a(n) = A111707(n) for n<=109, A111707(110) = 1;

0 <= a(n) <= 81, range = A174995;

a(10*n + n mod 10) = a(n);

a(A008592(n)) = 0;

A000030(a(A017281(n))) = A000030(A017281(n));

a(n) = a(A004086(n))*A168184(n);