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A072969
Least k > 0 such that the last digit of k^n is the same as the last digit of n^k.
0
1, 2, 3, 2, 5, 4, 7, 4, 9, 10, 1, 4, 7, 4, 5, 2, 3, 2, 9, 10, 1, 2, 3, 2, 5, 4, 7, 4, 9, 10, 1, 4, 7, 4, 5, 2, 3, 2, 9, 10, 1, 2, 3, 2, 5, 4, 7, 4, 9, 10, 1, 4, 7, 4, 5, 2, 3, 2, 9, 10, 1, 2, 3, 2, 5, 4, 7, 4, 9, 10, 1, 4, 7, 4, 5, 2, 3, 2, 9, 10, 1, 2, 3, 2, 5, 4, 7, 4, 9, 10, 1, 4, 7, 4, 5, 2, 3, 2, 9
OFFSET
1,2
FORMULA
a(n) is a periodic sequence with period (1, 2, 3, 2, 5, 4, 7, 4, 9, 10, 1, 4, 7, 4, 5, 2, 3, 2, 9, 10, ) of length 20
PROG
(PARI) a(n)=if(n<0, 0, k=1; while(abs(k^n%10-n^k%10)>0, s++); s)
CROSSREFS
Sequence in context: A365099 A342694 A212831 * A139712 A175856 A075365
KEYWORD
base,easy,nonn
AUTHOR
Benoit Cloitre, Aug 13 2002
STATUS
approved