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A046260
Largest palindromic substring in 2^n.
3
1, 2, 4, 8, 6, 3, 6, 8, 6, 5, 4, 8, 9, 9, 8, 8, 55, 131, 262, 242, 8, 9, 9, 838, 777, 55, 88, 77, 545, 9, 737, 474, 949, 858, 717, 383, 767, 9, 77, 888, 777, 255552, 111, 222, 444, 888, 77, 3553, 767, 21312, 42624, 99, 737, 474, 9, 797, 575, 8558, 7117, 646, 606, 939
OFFSET
0,2
LINKS
FORMULA
a(n) = A047813(A000079(n)). - Michel Marcus, Sep 19 2022
EXAMPLE
2^41 = 2199023{255552}.
PROG
(Python)
def c(s): return s[0] != "0" and s == s[::-1]
def a(n):
s = str(2**n)
ss = (s[i:j] for i in range(len(s)) for j in range(i+1, len(s)+1))
return max(int(w) for w in ss if c(w))
print([a(n) for n in range(62)]) # Michael S. Branicky, Sep 18 2022
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Patrick De Geest, Jun 15 1998
STATUS
approved