A104422 Numbers n such that n, p[n], p[n]+n, p[n]-n and p[n]*n all are 2-less.

5, 6, 16, 18, 30, 36, 78, 81, 83, 90, 94, 95, 100, 103, 104, 105, 108, 110, 111, 114, 131, 133, 136, 137, 139, 153, 154, 159, 160, 166, 488, 489, 495, 496, 498, 499, 500, 510, 511, 514, 640, 641, 643, 644, 645, 646, 650, 665, 669, 671, 680, 685, 687, 688, 690

Offset

1,1

Comments

From the first 3000 primes, only 182 are such that n, p[n], p[n]+n, p[n]-n and p[n]*n all are 2-less.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

id[x_]:=IntegerDigits[x]; pr[i_]:=Prime[i]; ra=Range[3000]; A104422=Select[ra, Position[Union[id[ # ], id[pr[ # ]], id[pr[ # ]+# ], id[pr[ # ]-# ], id[pr[ # ]*# ]], 2]=={}&]
tlQ[n_]:=DigitCount[n, 10, 2]==0; Select[Range[700], AllTrue[{#, p=Prime[#], p+#, p-#, p*#}, tlQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Mar 09 2018 *)

Crossrefs

Cf. A104419-A104428.

Sequence in context: A007430 A118712 A130878 * A026547 A081283 A058567

Adjacent sequences: A104419 A104420 A104421 * A104423 A104424 A104425

Keyword

nonn,base

Author

Zak Seidov, Mar 07 2005

Status

approved