A335072 Numbers with property that if you remove any digit and subtract 1 the result is prime.

33, 34, 36, 38, 43, 44, 46, 48, 63, 64, 66, 68, 83, 84, 86, 88, 124, 142, 144, 148, 184, 204, 244, 308, 320, 380, 424, 442, 444, 448, 484, 544, 608, 620, 680, 724, 742, 744, 804, 844, 908, 980, 1104, 1140, 2284, 2728, 2824, 3608, 3908, 4440, 4444, 4588, 4644

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..363 (all terms up to 10 million)

Example

33 is a term: remove any digit to be left with 3. Subtract 1 gives 2, which is prime.
4444 is a term: remove any digit to be left with 444. Subtract 1 to be left with 443, which is prime.
28 is not a term: remove any digit to be left with 2 or 8. Subtract 1 to be left with 1 or 7. 1 is not prime.

Maple

q:= n-> (s-> andmap(i-> isprime(parse(cat(0, s[1..i-1],
            s[i+1..-1]))-1), [$1..length(s)]))(""||n):
select(q, [$1..5000])[];  # Alois P. Heinz, May 30 2020

Mathematica

rdpQ[x_]:=AllTrue[FromDigits/@Table[Drop[IntegerDigits[x], {n}], {n, IntegerLength[ x]}]-1, PrimeQ]; Select[Range[4700], rdpQ] (* Harvey P. Dale, Aug 21 2020 *)

Crossrefs

Cf. A034895.

Sequence in context: A112817 A115394 A344143 * A260678 A329658 A344139

Adjacent sequences: A335069 A335070 A335071 * A335073 A335074 A335075

Keyword

nonn,base

Author

John Ryder, May 30 2020

Status

approved