A082794 Smallest multiple of n beginning with 4.

4, 4, 42, 4, 40, 42, 42, 40, 45, 40, 44, 48, 403, 42, 45, 48, 408, 414, 418, 40, 42, 44, 46, 48, 400, 416, 405, 420, 406, 420, 403, 416, 429, 408, 420, 432, 407, 418, 429, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 400, 408, 416, 424, 432, 440, 448, 456, 406, 413

Offset: 1

Author

Amarnath Murthy, Apr 20 2003

Keywords

• base
• easy
• nonn

Comments

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

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A082795, A082796, A082797, A082798.

Cf. A000030.

Programs

Haskell

a082794 n = until ((== 4) . a000030) (+ n) n
-- Reinhard Zumkeller, Mar 27 2012

Maple

a:= proc(n) option remember; local m; m:= 0;
      do m:=m+n; if (""||m)[1]="4" then break fi od; m
    end:
seq(a(n), n=1..60);  # Alois P. Heinz, Apr 04 2021

Mathematica

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

PARI

a(n)=forstep(k=n, 32*n, n, if(Vec(Str(k))[1]=="4", return(k))) \\ Charles R Greathouse IV, Mar 06 2011

Python

def a(n):
  kn = n
  while str(kn)[0] != '4': kn += n
  return kn
print([a(n) for n in range(1, 57)]) # Michael S. Branicky, Apr 04 2021

Extensions

More terms from Sean A. Irvine, Mar 06 2011