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A321570
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Least prime p such that p minus the multiplication of its digits is the n-th prime before p.
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3
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41, 23, 43, 3163, 29, 83, 47, 1543, 2713, 293, 4423, 383, 347, 4253, 1627, 653, 89, 277, 1637, 367, 673, 457, 2663, 2437, 1459, 647, 2269, 883, 2287, 2753, 1657, 3529, 6691, 2539, 8273, 2953, 389, 2377, 2647, 1489, 6427, 857, 479, 587, 19861, 2557, 677, 3457, 23981
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OFFSET
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1,1
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LINKS
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Paolo P. Lava, Table of n, a(n) for n = 1..350
Carlos Rivera, Puzzle 935. pi+SOD(pi)=p(i+n), The Prime Puzzles and Problems Connection.
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EXAMPLE
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a(1) = 43 because 43 - 4*3 = 31 that is the first prime before 43.
a(2) = 23 because 23 - 2*3 = 17 that is the second prime before 23.
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MAPLE
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P:=proc(q) local k, n, p; for n from 1 to q do
for k from n+1 to q do p:=ithprime(k);
if p-convert(convert(p, base, 10), `*`)=ithprime(k-n) then
lprint(n, p); break; fi; od; od; end: P(10^9);
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MATHEMATICA
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Array[Block[{p = 2}, While[p - Times @@ IntegerDigits@ p != NextPrime[p, -#], p = NextPrime@ p]; p] &, 49] (* Michael De Vlieger, Dec 17 2018 *)
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CROSSREFS
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Cf. A000040, A007954, A321568, A321569.
Sequence in context: A304581 A153682 A033361 * A196045 A196042 A177996
Adjacent sequences: A321567 A321568 A321569 * A321571 A321572 A321573
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KEYWORD
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base,nonn,easy
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AUTHOR
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Paolo P. Lava, Dec 17 2018
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STATUS
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approved
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