OFFSET
1,2
COMMENTS
a(6) is greater than 50000.
a(8) > 600000. - Giovanni Resta, Oct 08 2013
EXAMPLE
6 is in the sequence because 6^6 = 46656, which includes a 6 in the middle.
11 is not in the sequence, because even though the substring 11 appears twice in 11^11 = 285311670611, neither occurrence is precisely in the middle.
MATHEMATICA
Do[a = IntegerDigits[n^n]; b = Length[a]; c = IntegerLength[n]; If[EvenQ[b - c] && FromDigits[Take[a, {(b - c)/2 + 1, (b + c)/2}]] == n, Print[n]], {n, 50000}]
PROG
(PARI) is(n)=my(d=digits(n), D=digits(n^n)); if((#d+#D)%2, return(0)); for(i=1, #d, if(d[i]!=D[#D/2-#d/2+i], return(0))); 1 \\ Charles R Greathouse IV, Jul 30 2016
(Python)
from itertools import islice
def A229629(): # generator of terms
n = 1
while True:
s, sn = str(n**n), str(n)
l, ln = len(s), len(sn)
if (ln-l) % 2 == 0 and s[l//2-ln//2:l//2+(ln+1)//2] == sn: yield n
n += 1
CROSSREFS
KEYWORD
nonn,base,nice,more
AUTHOR
Farideh Firoozbakht, Oct 04 2013
EXTENSIONS
a(6)-a(7) from Giovanni Resta, Oct 08 2013
STATUS
approved