A072961 Numbers using only the digits 2 and 5, that are both curved and straight.

2, 5, 22, 25, 52, 55, 222, 225, 252, 255, 522, 525, 552, 555, 2222, 2225, 2252, 2255, 2522, 2525, 2552, 2555, 5222, 5225, 5252, 5255, 5522, 5525, 5552, 5555, 22222, 22225, 22252, 22255, 22522, 22525, 22552, 22555, 25222, 25225, 25252, 25255

Offset: 1

Author

Michael Joseph Halm, Aug 13 2002

Keywords

• easy
• nonn
• base

References

• M. J. Halm, Three Boxes, Puzzle-M Magazine (Apr. 1987).

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..8190

Programs

Magma

[n: n in [1..30000] | Set(Intseq(n)) subset {2,5}]; // Vincenzo Librandi, Aug 19 2016

Mathematica

Flatten[Table[FromDigits/@Tuples[{2, 5}, n], {n, 5}]] (* Vincenzo Librandi, Aug 19 2016 *)

Python

from itertools import product
A072961_list = [int(''.join(a)) for l in range(1,11) for a in product('25',repeat=l)] # Chai Wah Wu, May 12 2016