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A290347 Numerators of the Harary index for the n-halved cube graph. 1
0, 1, 6, 26, 100, 1096, 3920, 13936, 16544, 296256, 1068672, 11652352, 42658304, 1100471296, 4079876096, 15205967872, 56939270144, 642281037824, 2423854317568, 9177027411968, 34846713511936, 1459319692460032, 5568939824513024, 21297365878571008 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
Eric Weisstein's World of Mathematics, Harary Index
Eric Weisstein's World of Mathematics, Halved Cube Graph
FORMULA
a(n) = -2^(n-1)*HarmonicNumber(n)-2^(2*n-1)*Re(LerchPhi(2,1,n+1)).
EXAMPLE
First few terms are 0, 1, 6, 26, 100, 1096/3, 3920/3, 13936/3, 16544, 296256/5, ....
MATHEMATICA
Table[-2^(n - 1) HarmonicNumber[n] - 2^(2 n - 1) Re[LerchPhi[2, 1, n + 1]], {n, 20}] // Numerator
CROSSREFS
Cf. A290348 (denominators).
Sequence in context: A005022 A125107 A301476 * A034560 A307306 A143955
KEYWORD
nonn,frac
AUTHOR
Eric W. Weisstein, Jul 28 2017
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)