This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
import Data.List (elemIndex); import Data.Maybe (fromJust) a262461 = (+ 1) . fromJust . (`elemIndex` a262460_list)
The first terms of the sequence are: +----+---------+ | n | a(n) | +----+---------+ | 1 | 1 | | 2 | 10 | | 3 | 11 | | 4 | 12 | | 5 | 2 | | 6 | 20 | | 7 | 22 | | 8 | 21 | | 9 | 13 | | 10 | 3 | | 11 | 23 | | 12 | 30 | | 13 | 33 | | 14 | 31 | | 15 | 14 | | 16 | 4 | | 17 | 24 | | 18 | 32 | | 19 | 25 | | 20 | 5 | +----+---------+
import Data.List (inits, tails, intersect, delete)
a262323 n = a262323_list !! (n-1)
a262323_list = 1 : f "1" (map show [2..]) where
f xs zss = g zss where
g (ys:yss) | null (intersect its $ tail $ inits ys) &&
null (intersect tis $ init $ tails ys) = g yss
| otherwise = (read ys :: Int) : f ys (delete ys zss)
its = init $ tails xs; tis = tail $ inits xs
-- Reinhard Zumkeller, Sep 21 2015
See Links section.
def overlaps(a, b):
s, t = sorted([str(a), str(b)], key = lambda x: len(x))
if any(t.startswith(s[i:]) for i in range(len(s))): return True
return any(t.endswith(s[:i]) for i in range(1, len(s)+1))
def aupto(nn):
alst, aset = [1], {1}
for n in range(2, nn+1):
an = 1
while True:
while an in aset: an += 1
if overlaps(an, alst[-1]): alst.append(an); aset.add(an); break
an += 1
return alst
print(aupto(67)) # Michael S. Branicky, Jan 10 2021
. n | a(n) | A262412(n) n | a(n) | A262412(n) . ----+------+----------- ----+------+------------- . (25 | 26 | 222 ) . 1 | 1 | 1 26 | 24 | 220 . 2 | 3 | 10 27 | 29 | 1002 . 3 | 4 | 11 28 | 28 | 1001 . 4 | 5 | 12 29 | 27 | 1000 . 5 | 2 | 2 30 | 30 | 1010 . 6 | 6 | 20 31 | 31 | 1011 . 7 | 8 | 22 32 | 32 | 1012 . 8 | 7 | 21 33 | 34 | 1021 . 9 | 9 | 100 34 | 33 | 1020 . 10 | 10 | 101 35 | 37 | 1101 . 11 | 11 | 102 36 | 35 | 1022 . 12 | 12 | 110 37 | 38 | 1102 . 13 | 13 | 111 38 | 39 | 1110 . 14 | 14 | 112 39 | 36 | 1100 . 15 | 15 | 120 40 | 40 | 1111 . 16 | 16 | 121 41 | 41 | 1112 . 17 | 17 | 122 42 | 42 | 1120 . 18 | 18 | 200 43 | 43 | 1121 . 19 | 20 | 202 44 | 44 | 1122 . 20 | 19 | 201 45 | 46 | 1201 . 21 | 23 | 212 46 | 45 | 1200 . 22 | 21 | 210 47 | 49 | 1211 . 23 | 25 | 221 48 | 47 | 1202 . 24 | 22 | 211 49 | 50 | 1212 . 25 | 26 | 222 50 | 48 | 1210 . . (26 | 24 | 220 )
import Data.List (inits, tails, intersect, delete, genericIndex)
a262411 n = genericIndex a262411_list (n - 1)
a262411_list = 1 : f [1] (drop 2 a030341_tabf) where
f xs tss = g tss where
g (ys:yss) | null (intersect its $ tail $ inits ys) &&
null (intersect tis $ init $ tails ys) = g yss
| otherwise = (foldr (\t v -> 3 * v + t) 0 ys) :
f ys (delete ys tss)
its = init $ tails xs; tis = tail $ inits xs
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