A004176 Omit 1's from n.

0, 0, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 2, 3, 4, 5, 6, 7, 8, 9, 20, 2, 22, 23, 24, 25, 26, 27, 28, 29, 30, 3, 32, 33, 34, 35, 36, 37, 38, 39, 40, 4, 42, 43, 44, 45, 46, 47, 48, 49, 50, 5, 52, 53, 54, 55, 56, 57, 58, 59, 60, 6, 62, 63, 64, 65, 66, 67, 68, 69, 70, 7, 72, 73, 74

Offset

0,3

Comments

a(210) = 20 is the first term that differs from the variant "strip any leading or trailing digits 1 from n" [where digits 1 "protected" on both sides by digits different from 1 would be preserved]. Up to there, if a(n) is palindromic, then n is not in A359510, but if a(n) is non-palindromic and n is prime, then n is in A359510. - M. F. Hasler, Jan 23 2023

Links

Rémy Sigrist, Table of n, a(n) for n = 0..10000

Mathematica

Table[FromDigits[DeleteCases[IntegerDigits[n], 1]], {n, 0, 3000}] (* Zak Seidov, Dec 08 2010 *)

Prog

(PARI) a(n) = fromdigits(select(d -> d!=1, digits(n))) \\ Rémy Sigrist, Jul 13 2019
(Python) def A004176(n): return int(s) if (s:=str(n).replace('1', '')) else 0 # M. F. Hasler, Jan 23 2023

Crossrefs

See A004720 for another version.

Cf. A359510 (numbers that can't be written as a palindromic product).

Sequence in context: A103303 A297232 A093691 * A085124 A252648 A054054

Adjacent sequences: A004173 A004174 A004175 * A004177 A004178 A004179

Keyword

nonn,base,look

Author

N. J. A. Sloane

Status

approved