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

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);

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Prog

(Haskell)
a169669 n = a000030 n * mod n 10
-- Reinhard Zumkeller, Apr 29 2015
(Python)
def a(n): return int(str(n)[0])*(n%10)
print([a(n) for n in range(81)]) # Michael S. Branicky, Jul 13 2022

Crossrefs

Cf. A088133.

Cf. A000030, A008592, A010879, A111707, A115300, A174995.

Sequence in context: A292678 A072595 A334832 * A111707 A115300 A085942

Adjacent sequences: A169666 A169667 A169668 * A169670 A169671 A169672

Keyword

base,nonn,hear,look

Author

Reinhard Zumkeller, Apr 05 2010

Status

approved