The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A196421

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A196421

a(n) = prime(n)*T(n), where T = A000217.
(history; published version)

#36 by Alois P. Heinz at Thu Sep 01 20:02:26 EDT 2022

STATUS

proposed

approved

#35 by Michael S. Branicky at Thu Sep 01 19:31:22 EDT 2022

STATUS

editing

proposed

#34 by Michael S. Branicky at Thu Sep 01 19:31:20 EDT 2022

PROG

(Python)

from sympy import prime

def a(n): return prime(n) * n*(n+1)//2

print([a(n) for n in range(1, 41)]) # Michael S. Branicky, Sep 01 2022

STATUS

approved

editing

#33 by Bruno Berselli at Tue May 15 06:42:21 EDT 2018

STATUS

proposed

approved

#32 by Michel Marcus at Tue May 15 02:54:59 EDT 2018

STATUS

editing

proposed

#31 by Michel Marcus at Tue May 15 02:54:51 EDT 2018

CROSSREFS

Subsequence of A085783. - Michel Marcus, May 15 2018

STATUS

approved

editing

#30 by N. J. A. Sloane at Tue Sep 05 12:40:51 EDT 2017

STATUS

editing

approved

#29 by N. J. A. Sloane at Tue Sep 05 12:40:46 EDT 2017

COMMENTS

This idea sequence is mentioned in A077320. - Omar E. Pol, Mar 12 2012

STATUS

proposed

editing

#28 by Bruno Berselli at Tue Sep 05 11:31:19 EDT 2017

STATUS

editing

proposed

Discussion

Tue Sep 05

11:56

Joerg Arndt: What's "This idea" in the comment?

12:00

Michel Marcus: Maybe " ... sequence was motivated by ..."

#27 by Bruno Berselli at Tue Sep 05 11:30:54 EDT 2017

NAME

N-th prime times n-th triangular number

a(n) = prime(n)*T(n), where T = A000217.

FORMULA

a(n) ~ 0.5 n^3 log n. [_- _Charles R Greathouse IV_, Nov 22 2011]

EXAMPLE

The 4th prime is 7; , the 4th triangular number is 10; , therefore a(4) = 7 * 10 = 70.

CROSSREFS

Cf. A000040, A000217.

STATUS

reviewed

editing