A039690 Ambitious numbers: numbers n with the property that if a number ends in n then it is divisible by n.

1, 2, 5, 10, 20, 25, 50, 100, 125, 200, 250, 500, 1000, 1250, 2000, 2500, 5000, 10000, 12500, 20000, 25000, 50000, 100000, 125000, 200000, 250000, 500000, 1000000, 1250000, 2000000, 2500000, 5000000, 10000000, 12500000, 20000000, 25000000

Offset: 1

Author

Erich Friedman

Keywords

• nonn
• base
• easy

Comments

Number whose 10's complement (A089186) is a multiple of it. 125 is a member as its 10's complement is 1000-125 = 875 = 125*7. - Amarnath Murthy, Mar 08 2002

Examples

			If a number ends in 2 then it is even and so is divisible by 2, so 2 is in the sequence.
		

References

• P. J. Davis and R. Hersh, The Mathematical Experience, Birkhäuser, Boston and Basel, 1981; see pp. 293-298.

Links

• Problem of the week, Web site - problem 881
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,10).

Crossrefs

Cf. A039690, A089186.

Programs

Mathematica

LinearRecurrence[{0,0,0,0,10},{1,2,5,10,20,25,50,100,125},40] (* Harvey P. Dale, Sep 08 2018 *)

Formula

Consists of the numbers 1, 2, 5, 25 or 125 times a power of 10.

a(n) = 10*a(n-5). - Wesley Ivan Hurt, May 03 2023

Extensions

Entry revised by N. J. A. Sloane, Aug 03 2004