A215728 a(n) is the smallest m for which 5^m contains n consecutive identical digits.

0, 11, 50, 95, 125, 1087, 2786, 2790, 2796, 2797, 2802, 2803, 1040703, 5547565, 7761841, 17876345

Offset: 1

Author

V. Raman, Aug 22 2012

Keywords

• nonn
• base
• more

Comments

a(13) > 893000. - Chai Wah Wu, Dec 17 2014

Crossrefs

Cf. A215734, A045875.

Programs

Python

def A215728(n):
    l, x = [str(d)*n for d in range(10)], 1
    for m in range(10**9):
        s = str(x)
        for k in l:
            if k in s:
                return m
        x *= 5
    return 'search limit reached'
# Chai Wah Wu, Dec 17 2014

Extensions

a(13)-a(14) from Giovanni Resta, Apr 19 2016

a(15)-a(16) from Bert Dobbelaere, Feb 13 2019