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Least multiple of prime(n) ending in digit 9.
1

%I #8 Jan 29 2023 09:43:55

%S 49,99,39,119,19,69,29,279,259,369,129,329,159,59,549,469,639,219,79,

%T 249,89,679,909,309,749,109,339,889,1179,959,139,149,1359,1099,489,

%U 1169,519,179,1629,1719,579,1379,199,1899,669,1589,229,699,239,2169,2259

%N Least multiple of prime(n) ending in digit 9.

%C Subsidiary sequences: (1) least multiple of prime(n) ending in 2 or 3 or ..., or 8; (2) divide the above sequences by prime(n).

%t f[n_] := Block[{k = 1, p = Prime[n]}, While[Mod[k*p, 10] != 9, k++ ]; k*p]; Table[ f[n], {n, 4, 54}] (* _Robert G. Wilson v_, Nov 17 2005 *)

%o (PARI) a(n) = my(p=prime(n), k=1); while(((k*p) % 10) != 9, k++); k*p; \\ _Michel Marcus_, Jan 29 2023

%Y Cf. A114011, A114012.

%K base,nonn

%O 4,1

%A _Amarnath Murthy_, Nov 12 2005

%E More terms from _Robert G. Wilson v_, Nov 17 2005