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A083119 Sum of n terms from the n-th term is a square: a(1), a(2) + a(3), a(3) + a(4) + a(5),..., a(n) + a(n+1) + ...+ a(2n-1) are squares. 1
1, 2, 7, 3, 6, 4, 12, 5, 9, 8, 11, 10, 26, 13, 18, 14, 35, 15, 19, 16, 48, 17, 25, 20, 23, 21, 40, 22, 28, 24, 33, 27, 71, 29, 51, 30, 32, 31, 37, 34, 86, 36, 67, 38, 95, 39, 47, 41, 42, 43, 45, 44, 113, 46, 65, 49, 121, 50, 55, 52, 132, 53, 63, 54, 58 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(2n) is the smallest number that has not occurred earlier and a(2n+1) is the smallest number (again not included earlier) required to satisfy the requirement. Another permutation of natural numbers.

LINKS

Table of n, a(n) for n=1..65.

PROG

(GAP) sq := List([1..100], x->x^2); l := [1]; k := 2;

repeat m := Minimum(Difference([1..Size(l)+1], l)); Add(l, m);

sum := Sum(List([k..2*k-2], x->l[x]));

m := sq[PositionProperty(sq, x->x>sum and not x-sum in l)]-sum;

Add(l, m); k := k+1;

until k = 50; l; - Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jun 29 2005

CROSSREFS

Cf. A083121.

Sequence in context: A082737 A104957 A329333 * A246163 A198388 A011304

Adjacent sequences:  A083116 A083117 A083118 * A083120 A083121 A083122

KEYWORD

nonn

AUTHOR

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Apr 23 2003

EXTENSIONS

More terms from Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jun 29 2005

STATUS

approved

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Last modified April 6 16:14 EDT 2020. Contains 333276 sequences. (Running on oeis4.)