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%I #16 Apr 26 2021 17:05:01
%S 0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,
%T 0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,
%U 0,0,1,1,1,1,1,1,1,2,1,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0
%N Number of times 7 appears in decimal expansion of n.
%e a(0) = 0 since the decimal representation of 0 does not contain the digit 7.
%e a(7) = 1 since 7 appears once in the decimal expansion of 7.
%t Array[ DigitCount[#, 10, 7] &, 105, 0]
%o (PARI) a(n) = #select(x->x==7, digits(n)); \\ _Michel Marcus_, Jul 20 2018
%Y Cf. A043517, A043518, A043519, A043520.
%Y Cf. A055641, A268643, A316863, A316864, A316865, A316866, A316867, A316869, A102683.
%Y Cf. A079692.
%K base,easy,nonn
%O 0,78
%A _Robert G. Wilson v_, Jul 15 2018
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