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A217395
Numbers starting with 3.
11
3, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342
OFFSET
1,1
COMMENTS
The lower and upper asymptotic densities of this sequence are 1/27 and 5/18, respectively. - Amiram Eldar, Feb 27 2021
FORMULA
a(n) = n + (26*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 16 2023
MATHEMATICA
Select[Range[1000], IntegerDigits[#][[1]] == 3 &] (* T. D. Noe, Oct 02 2012 *)
PROG
(Python)
def agen():
yield 3
digits, adder = 1, 30
while True:
for i in range(10**digits): yield adder + i
digits, adder = digits+1, adder*10
g = agen()
print([next(g) for i in range(54)]) # Michael S. Branicky, Mar 30 2021
(Python)
def A217395(n): return n+26*10**(len(str(9*n-8))-1)//9 # Chai Wah Wu, Sep 11 2024
(PARI) a(n) = n + 26*10^logint(9*n, 10)\9; \\ Kevin Ryde, Mar 30 2021
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Jeremy Gardiner, Oct 02 2012
STATUS
approved