A097387 -id:A097387 - cp's OEIS frontend

A097385 a(n) = (largest digit of n)^(smallest digit of n) + n.

1, 2, 6, 30, 260, 3130, 46662, 823550, 16777224, 387420498, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 21, 23, 26, 32, 40, 50, 62, 76, 92, 110, 31, 34, 41, 60, 98, 160, 252, 380, 550, 768, 41, 45, 58, 107, 300, 670, 1342, 2448, 4144, 6610, 51, 56, 77, 178, 679, 3180

Offset: 0

Jason Earls, Aug 18 2004

			a(2345) = 2370 because 5^2 + 2345 = 2370.

Mia Boudreau, Table of n, a(n) for n = 0..10000

Cf. A054054, A054055, A097386, A097387.

def a(n): return int(max(s:=str(n)))**int(min(s)) + n
print([a(n) for n in range(56)]) # Michael S. Branicky, Jul 21 2025

a(n) = A054055(n)^A054054(n) + n. - Mia Boudreau, Jul 17 2025

a(0) corrected and 2 terms merged by Mia Boudreau, Jul 16 2025

A097386 Numbers n such that (largest digit of n)^(smallest digit of n) + n is prime.

Original entry on oeis.org

1, 10, 21, 30, 32, 40, 43, 60, 61, 65, 70, 81, 92, 100, 102, 106, 108, 130, 150, 152, 161, 172, 174, 180, 183, 185, 190, 210, 221, 232, 240, 250, 252, 270, 280, 283, 285, 292, 298, 306, 310, 322, 330, 354, 361, 372, 376, 381, 394, 400, 408, 420, 423, 430, 460

Offset: 1

Jason Earls, Aug 18 2004

No term ends in 9. Conjecture: Let f(x)=(largest digit of x)^(smallest digit of x) + x. There are infinitely many positive integers n such that f(n) and f(n+1) are both prime; see A097387.

			1272 is in the sequence because 7^2 + 1272 = 1321, a prime.

Cf. A054054, A054055, A097385, A097387.

okQ[n_]:=Module[{idn=IntegerDigits[n]},PrimeQ[Max[idn]^Min[idn]+n]]
Select[Range[500],okQ] (* Harvey P. Dale, Dec 11 2010 *)

Corrected by T. D. Noe, Oct 25 2006

cp's OEIS Frontend

A097385 a(n) = (largest digit of n)^(smallest digit of n) + n.

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