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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: Terms will always be multiples of ten. Aug 21, 2004: Dean Hickerson proved this.

LINKS

Table of n, a(n) for n=1..39.

EXAMPLE

640 is in the sequence because 6^0 + 640 = 641 and 6^1 + 641 = 647, both prime.

CROSSREFS

Cf. A054054, A054055, A097385, A097386.

Sequence in context: A020868 A223461 A088943 * A057096 A246774 A341597

Adjacent sequences:  A097384 A097385 A097386 * A097388 A097389 A097390

KEYWORD

base,easy,nonn

AUTHOR

Jason Earls, Aug 18 2004

STATUS

approved

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Last modified June 21 12:39 EDT 2021. Contains 345364 sequences. (Running on oeis4.)