A104427 Numbers n such that n, p[n], p[n]+n, p[n]-n and p[n]*n all are 7-less.

1, 2, 3, 5, 10, 11, 13, 23, 24, 29, 30, 32, 35, 38, 43, 46, 51, 60, 62, 81, 82, 98, 100, 140, 146, 180, 185, 188, 189, 190, 191, 200, 202, 205, 209, 215, 221, 226, 231, 246, 252, 254, 255, 261, 266, 281, 282, 291, 293, 301, 320, 321, 323, 346, 369, 381, 382, 391

Offset

1,2

Comments

From the first 3000 primes, only 200 are such that n, p[n], p[n]+n, p[n]-n and p[n]*n all are 7-less.

Links

Table of n, a(n) for n=1..58.

Mathematica

id[x_]:=IntegerDigits[x]; pr[i_]:=Prime[i]; ra=Range[3000]; A104427=Select[ra, Position[Union[id[ # ], id[pr[ # ]], id[pr[ # ]+# ], id[pr[ # ]-# ], id[pr[ # ]*# ]], 7]=={}&]

Crossrefs

Cf. A104419-A104428.

Sequence in context: A219860 A076681 A047604 * A259732 A192229 A233696

Adjacent sequences: A104424 A104425 A104426 * A104428 A104429 A104430

Keyword

nonn,base

Author

Zak Seidov, Mar 07 2005

Status

approved