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A035333 Concatenation of two or more consecutive positive integers. 10
12, 23, 34, 45, 56, 67, 78, 89, 123, 234, 345, 456, 567, 678, 789, 910, 1011, 1112, 1213, 1234, 1314, 1415, 1516, 1617, 1718, 1819, 1920, 2021, 2122, 2223, 2324, 2345, 2425, 2526, 2627, 2728, 2829, 2930, 3031, 3132, 3233, 3334, 3435, 3456, 3536, 3637, 3738 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
PROG
(Python)
import heapq
from itertools import islice
def agen():
c = 12
h = [(c, 1, 2)]
nextcount = 3
while True:
(v, s, l) = heapq.heappop(h)
yield v
if v >= c:
c = int(str(c) + str(nextcount))
heapq.heappush(h, (c, 1, nextcount))
nextcount += 1
l += 1; v = int(str(v)[len(str(s)):] + str(l)); s += 1
heapq.heappush(h, (v, s, l))
print(list(islice(agen(), 47))) # Michael S. Branicky, Dec 23 2021
CROSSREFS
For concatenations of exactly k consecutive integers see A000027 (k=1), A127421 (k=2), A001703 (k=3), A279204 (k=4).
See also A007908 for concatenation of 1 through n.
For primes see A052087.
All of A007908, A052087, A053067, A279610 are subsequences.
Sequence in context: A228157 A363820 A072485 * A001704 A127421 A112131
KEYWORD
easy,nonn,base
AUTHOR
EXTENSIONS
Edited by Charles R Greathouse IV, Apr 28 2010
Corrected by Paul Tek, Jun 08 2013
STATUS
approved

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Last modified June 25 18:50 EDT 2024. Contains 373707 sequences. (Running on oeis4.)