A074757 Numbers n such that tau(n) = (tau(n+1)+tau(n-1))/2.

34, 46, 62, 74, 86, 94, 142, 188, 202, 214, 218, 231, 243, 244, 262, 278, 302, 356, 375, 394, 422, 423, 428, 436, 446, 459, 478, 494, 584, 596, 604, 621, 628, 634, 664, 698, 716, 837, 861, 885, 903, 916, 922, 944, 956, 982, 1004, 1017, 1018, 1028, 1042, 1052

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Vaclav Kotesovec, Plot of a(n)/n for n = 1..1000000

Vaclav Kotesovec, Plot of a(n)/(n*log(log(n))) for n = 1..1000000

Formula

a(n) seems to be asymptotic to c*n with c around 23. [This conjecture is false. The limit a(n)/n, if it exists, is > 29, see graphs. - Vaclav Kotesovec, Feb 14 2019]

Mathematica

okQ[{a_, b_, c_}]:=(a+c)/2==b; Flatten[Position[Partition[DivisorSigma[0, Range[1100]], 3, 1], _?okQ]]+1 (* Harvey P. Dale, Aug 17 2013 *)

Crossrefs

Cf. A090502.

Sequence in context: A275194 A341173 A352787 * A211710 A039327 A043150

Adjacent sequences: A074754 A074755 A074756 * A074758 A074759 A074760

Keyword

easy,nonn

Author

Benoit Cloitre, Sep 28 2002

Status

approved