

A215732


a(n) is the first digit to appear n times in succession in a power of 2.


19



1, 5, 7, 5, 6, 8, 7, 1, 9, 9, 6, 3, 2, 9, 1
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OFFSET

1,2


COMMENTS

Assumes that there are no 2 digits that appear n times in succession for the first time in the same power of 2.  Chai Wah Wu, Apr 26 2019


LINKS

Table of n, a(n) for n=1..15.


EXAMPLE

2^16 = 65536 is the first power of 2 with a repeated digit (cf. A045875), with 5 repeated, so a(2) = 5.  N. J. A. Sloane, Aug 23 2012


MATHEMATICA

n = 1; x = 1; lst = {};
For[i = 1, i <= 10000, i++,
z = Split[IntegerDigits[x]]; a = Length /@ z; b = Max[a];
For[j = n, j <= b, j++,
AppendTo[lst, First[First[Part[z, First[Position[a, b]]]]]]; n++
]; x = 2 x ]; lst (* Robert Price, Mar 16 2019 *)


PROG

(Python)
def A215732(n):
l, x = [str(d)*n for d in range(10)], 1
for m in range(10**9):
s = str(x)
for k in range(10):
if l[k] in s:
return k
x *= 2
return 'search limit reached'
# Chai Wah Wu, Dec 17 2014


CROSSREFS

Cf. A045875, A215733, A215734, A215735.
Sequence in context: A011205 A167133 A144567 * A010718 A247872 A306400
Adjacent sequences: A215729 A215730 A215731 * A215733 A215734 A215735


KEYWORD

nonn,base,hard,more


AUTHOR

V. Raman, Aug 22 2012


EXTENSIONS

a(11)a(13) added by T. D. Noe, Sep 04 2012
a(14) added by T. D. Noe, Sep 06 2012
a(15) from Bert Dobbelaere, Feb 25 2019


STATUS

approved



