The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A130901 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A130901

a(n) = Sum_{k=1..9} floor(10^n / k).
(history; published version)

#23 by Harvey P. Dale at Sun May 12 02:05:32 EDT 2024

STATUS

editing

approved

#22 by Harvey P. Dale at Sun May 12 02:05:28 EDT 2024

MATHEMATICA

LinearRecurrence[{11, -10, -1, 11, -10}, {1, 26, 281, 2827, 28288, 282895, 2828967, 28289681}, 20] (* Harvey P. Dale, May 12 2024 *)

STATUS

approved

editing

#21 by Bruno Berselli at Tue Jan 26 10:50:54 EST 2021

STATUS

reviewed

approved

#20 by Joerg Arndt at Tue Jan 26 10:46:25 EST 2021

STATUS

proposed

reviewed

#19 by Michel Marcus at Tue Jan 26 09:37:44 EST 2021

STATUS

editing

proposed

#18 by Michel Marcus at Tue Jan 26 09:37:36 EST 2021

PROG

(PARI) a(n) = sum(k=1, 9, 10^n\k); \\ Michel Marcus, Jan 26 2021

STATUS

proposed

editing

#17 by Michael S. Branicky at Tue Jan 26 09:14:02 EST 2021

STATUS

editing

proposed

#16 by Michael S. Branicky at Tue Jan 26 09:13:34 EST 2021

DATA

1, 26, 281, 2827, 28288, 282895, 2828967, 28289681, 282896824, 2828968252, 28289682538, 282896825395, 2828968253967, 28289682539681, 282896825396824, 2828968253968252, 28289682539682538, 282896825396825395, 2828968253968253967, 28289682539682539681

PROG

(Python)

def a(n): return sum(10**n//k for k in range(1, 10))

print([a(n) for n in range(20)]) # Michael S. Branicky, Jan 26 2021

STATUS

approved

editing

#15 by Alois P. Heinz at Thu Jan 14 20:18:46 EST 2021

STATUS

editing

approved

#14 by Alois P. Heinz at Thu Jan 14 20:18:42 EST 2021

KEYWORD

nonn,easy,changed

STATUS

proposed

editing