The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A081523 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A081523

Sum of terms in row n of A081521.
(history; published version)

#6 by Peter Luschny at Sun May 24 04:00:35 EDT 2020

STATUS

reviewed

approved

#5 by Joerg Arndt at Sun May 24 01:44:35 EDT 2020

STATUS

proposed

reviewed

Discussion

Sun May 24

01:58

Michel Marcus: needs A081521 current draft

#4 by Jinyuan Wang at Sat May 23 23:37:40 EDT 2020

STATUS

editing

proposed

#3 by Jinyuan Wang at Sat May 23 23:37:06 EDT 2020

DATA

1, 4, 12, 16, 20, 54, 35, 64, 72, 130, 77

PROG

(PARI) a(n) = {my(m=n*(n-1)/2, v); forstep(k=m+n/(2-n%2), oo, n, v=List([]); for(i=2, k-m, if(gcd(n, i)==1, listput(v, i))); if(#v>n-2, forsubset([#v, n-1], w, if(r=1+sum(i=1, n-1, v[w[i]])==k, return(k))))); } \\ Jinyuan Wang, May 23 2020

KEYWORD

more,nonn

nonn,more

EXTENSIONS

a(8)-a(11) from Jinyuan Wang, May 23 2020

STATUS

approved

editing

#2 by N. J. A. Sloane at Thu Dec 05 19:56:02 EST 2013

AUTHOR

_Amarnath Murthy (amarnath_murthy(AT)yahoo.com), _, Mar 27 2003

Discussion

Thu Dec 05

19:56

OEIS Server: https://oeis.org/edit/global/2075

#1 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

NAME

Sum of terms in row n of A081521.

DATA

1, 4, 12, 16, 20, 54, 35

OFFSET

1,2

CROSSREFS

Cf. A081521, A081522, A081524.

KEYWORD

more,nonn

AUTHOR

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 27 2003

STATUS

approved