

A080037


a(0)=2; for n > 0, a(n) = n + floor(sqrt(4n3)) + 2.


19



2, 4, 6, 8, 9, 11, 12, 14, 15, 16, 18, 19, 20, 22, 23, 24, 25, 27, 28, 29, 30, 32, 33, 34, 35, 36, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 74, 75, 76, 77, 78, 79, 80, 81, 83, 84, 85, 86, 87, 88, 89, 90, 92
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OFFSET

0,1


COMMENTS

a(0)=2, a(1)=4; for n > 2, a(n) = a(n1) + 1 if n is already in the sequence, a(n) = a(n1) + 2 otherwise. [corrected by Jon E. Schoenfield, Jun 24 2018]
For n > 0, a(n) = ceiling((1 + sqrt(n))^2). Empirical observation.  Ronald S. Tiberio, Jun 24 2018
For n > 0, a(n) is the minimal number of thumbtacks needed to secure n square sheets of paper on a bulletin board  one thumbtack in each corner of each sheet  slight overlap allowed so that one thumbtack can secure up to four sheets.  Ronald S. Tiberio, Jun 24 2018


LINKS

Table of n, a(n) for n=0..73.
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, J. Integer Seqs., Vol. 6 (2003), #03.2.2.
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, arXiv:math/0305308 [math.NT], 2003.


CROSSREFS

Cf. A000267, A080036.
Sequence in context: A217352 A036627 A191982 * A184012 A186354 A186149
Adjacent sequences: A080034 A080035 A080036 * A080038 A080039 A080040


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Mar 14 2003


STATUS

approved



