A208259 Numbers starting and ending with digit 1.

1, 11, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 1001, 1011, 1021, 1031, 1041, 1051, 1061, 1071, 1081, 1091, 1101, 1111, 1121, 1131, 1141, 1151, 1161, 1171, 1181, 1191, 1201, 1211, 1221, 1231, 1241, 1251, 1261, 1271, 1281, 1291, 1301, 1311, 1321, 1331

Offset

1,2

Comments

A000030(a(n)) = a(n) mod 10 = 1. - Reinhard Zumkeller, Jul 16 2014

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Prog

(Haskell)
a208259 n = a208259_list !! (n-1)
a208259_list = 1 : map ((+ 1) . (* 10)) a131835_list
-- Reinhard Zumkeller, Jul 16 2014
(Python)
from itertools import count, islice, product
def agen(): # generator of terms
    yield 1
    yield from (int("1"+"".join(m)+"1") for d in count(0) for m in product("0123456789", repeat=d))
print(list(islice(agen(), 46))) # Michael S. Branicky, Jun 13 2026

Crossrefs

Intersection of A017281 and A131835. Union of A062332 and A208260.

Supersequence of A208262 (numbers with all divisors starting and ending with digit 1).

Cf. A062332 (primes starting and ending with a digit 1), A208260 (nonprime numbers starting and ending with a digit 1).

Cf. A017281, A131835, A000030.

Sequence in context: A038444 A115824 A364326 * A043036 A072001 A265510

Adjacent sequences: A208256 A208257 A208258 * A208260 A208261 A208262

Keyword

nonn,base

Author

Jaroslav Krizek, Feb 24 2012

Status

approved