A082794 - OEIS

%I #25 Apr 04 2021 10:12:06

%S 4,4,42,4,40,42,42,40,45,40,44,48,403,42,45,48,408,414,418,40,42,44,

%T 46,48,400,416,405,420,406,420,403,416,429,408,420,432,407,418,429,40,

%U 41,42,43,44,45,46,47,48,49,400,408,416,424,432,440,448,456,406,413

%N Smallest multiple of n beginning with 4.

%C a(n) is in {n, 2n, 3n, 4n, 5n, 6n, 7n, 8n, 11n, 12n, 13n, 14n, 15n, 16n, 21n, 22n, 23n, 24n, 31n, 32n}. - _Charles R Greathouse IV_, Mar 06 2011

%H Vincenzo Librandi, <a href="/A082794/b082794.txt">Table of n, a(n) for n = 1..1000</a>

%p a:= proc(n) option remember; local m; m:= 0;

%p       do m:=m+n; if (""||m)[1]="4" then break fi od; m

%p     end:

%p seq(a(n), n=1..60);  # _Alois P. Heinz_, Apr 04 2021

%t f[n_] := Block[{m = n}, While[ First@ IntegerDigits@ m != 4, m += n]; m]; Array[f, 56] (* _Robert G. Wilson v_ *)

%o (PARI) a(n)=forstep(k=n, 32*n, n, if(Vec(Str(k))[1]=="4", return(k))) \\ _Charles R Greathouse IV_, Mar 06 2011

%o (Haskell)

%o a082794 n = until ((== 4) . a000030) (+ n) n

%o -- _Reinhard Zumkeller_, Mar 27 2012

%o (Python)

%o def a(n):

%o   kn = n

%o   while str(kn)[0] != '4': kn += n

%o   return kn

%o print([a(n) for n in range(1, 57)]) # _Michael S. Branicky_, Apr 04 2021

%Y Cf. A082795, A082796, A082797, A082798.

%Y Cf. A000030.

%K base,easy,nonn

%O 1,1

%A _Amarnath Murthy_, Apr 20 2003

%E More terms from _Sean A. Irvine_, Mar 06 2011