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A023858 a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k = floor((n+1)/2), t = A023531. 0
0, 1, 2, 0, 1, 2, 3, 4, 6, 2, 3, 4, 5, 7, 9, 11, 13, 5, 6, 8, 10, 12, 14, 16, 18, 20, 23, 11, 13, 15, 17, 19, 21, 23, 26, 29, 32, 35, 38, 20, 22, 24, 26, 29, 32, 35, 38, 41, 44, 47, 50, 53, 56, 32, 35, 38, 41, 44, 47, 50, 53, 56, 59, 62, 66, 70, 74, 78, 82, 50, 53, 56, 59, 62, 65, 68, 72, 76, 80, 84, 88, 92 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..82.

FORMULA

a(n) = Sum_{k=1..floor((n+1)/2)} A023531(n+1-k). - Sean A. Irvine, Jun 11 2019

MATHEMATICA

Array[Sum[k Boole@ IntegerQ@ Sqrt[8 # + 9] &[# + 1 - k], {k, Floor[(# + 1)/2]}] &, 82] (* Michael De Vlieger, Jun 12 2019 *)

CROSSREFS

Sequence in context: A135317 A227179 A115218 * A011118 A304784 A131644

Adjacent sequences:  A023855 A023856 A023857 * A023859 A023860 A023861

KEYWORD

nonn,changed

AUTHOR

Clark Kimberling

EXTENSIONS

Missing a(21)=10 inserted and title simplified by Sean A. Irvine, Jun 11 2019

STATUS

approved

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Last modified June 25 22:14 EDT 2019. Contains 324357 sequences. (Running on oeis4.)