A321570 Least prime p such that p minus the multiplication of its digits is the n-th prime before p.

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

Offset

1,1

Links

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.

Example

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.

Maple

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);

Mathematica

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

Crossrefs

Cf. A000040, A007954, A321568, A321569.

Sequence in context: A304581 A153682 A033361 * A196045 A196042 A177996

Adjacent sequences: A321567 A321568 A321569 * A321571 A321572 A321573

Keyword

base,nonn,easy

Author

Paolo P. Lava, Dec 17 2018

Status

approved