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

1,2

Comments

Number whose 10's complement 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

References

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

Links

Table of n, a(n) for n=1..36.

Problem of the week, Web site - problem 881

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,10).

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

Example

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

Mathematica

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

Crossrefs

Cf. A039690.

Sequence in context: A018327 A285571 A000099 * A243938 A365630 A126105

Adjacent sequences: A039687 A039688 A039689 * A039691 A039692 A039693

Keyword

nonn,base,easy

Author

Erich Friedman

Extensions

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

Status

approved