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A097387
Let f(x)=(largest digit of x)^(smallest digit of x) + x (A097385). Sequence gives numbers n such that f(n) and f(n+1) are both prime.
2
60, 460, 640, 820, 1360, 1480, 1620, 1870, 2110, 2380, 3460, 3630, 3880, 4560, 4650, 5640, 5650, 5860, 6210, 6310, 6360, 6420, 7480, 8170, 8680, 8830, 11680, 11830, 12280, 12640, 12820, 13780, 14620, 15460, 15640, 15660, 15880, 16410, 16420
OFFSET
1,1
COMMENTS
Conjecture: Terms will always be multiples of ten. Aug 21, 2004: Dean Hickerson proved this.
EXAMPLE
640 is in the sequence because 6^0 + 640 = 641 and 6^1 + 641 = 647, both prime.
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Jason Earls, Aug 18 2004
STATUS
approved