A321570 - OEIS

%I #13 Dec 28 2018 18:59:11

%S 41,23,43,3163,29,83,47,1543,2713,293,4423,383,347,4253,1627,653,89,

%T 277,1637,367,673,457,2663,2437,1459,647,2269,883,2287,2753,1657,3529,

%U 6691,2539,8273,2953,389,2377,2647,1489,6427,857,479,587,19861,2557,677,3457,23981

%N Least prime p such that p minus the multiplication of its digits is the n-th prime before p.

%H Paolo P. Lava, <a href="/A321570/b321570.txt">Table of n, a(n) for n = 1..350</a>

%H Carlos Rivera, <a href="https://www.primepuzzles.net/puzzles/puzz_935.htm">Puzzle 935. pi+SOD(pi)=p(i+n)</a>, The Prime Puzzles and Problems Connection.

%e a(1) = 43 because 43 - 4*3 = 31 that is the first prime before 43.

%e a(2) = 23 because 23 - 2*3 = 17 that is the second prime before 23.

%p P:=proc(q) local k,n,p; for n from 1 to q do

%p for k from n+1 to q do p:=ithprime(k);

%p if p-convert(convert(p,base,10),`*`)=ithprime(k-n) then

%p lprint(n,p); break; fi; od; od; end: P(10^9);

%t Array[Block[{p = 2}, While[p - Times @@ IntegerDigits@ p != NextPrime[p, -#], p = NextPrime@ p]; p] &, 49] (* _Michael De Vlieger_, Dec 17 2018 *)

%Y Cf. A000040, A007954, A321568, A321569.

%K base,nonn,easy

%O 1,1

%A _Paolo P. Lava_, Dec 17 2018