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A060469 Smallest positive a(n) such that number of solutions to a(n) = a(j)+a(k) j<k<n is one or less. 8
1, 2, 3, 4, 6, 8, 11, 13, 16, 18, 23, 25, 28, 30, 35, 37, 40, 42, 47, 49, 52, 54, 59, 61, 64, 66, 71, 73, 76, 78, 83, 85, 88, 90, 95, 97, 100, 102, 107, 109, 112, 114, 119, 121, 124, 126, 131, 133, 136, 138, 143, 145, 148, 150, 155, 157, 160, 162, 167, 169, 172, 174 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers {1,4,6,11} mod 12 plus {2,3,8}.

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

FORMULA

a(n) = a(n-1)+a(n-4)-a(n-5) for n>9. - Colin Barker, Feb 27 2015

G.f.: x*(2*x^10+x^8+x^7+2*x^6+x^5+x^4+x^3+x^2+x+1) / ((x-1)^2*(x+1)*(x^2+1)). - Colin Barker, Feb 27 2015

EXAMPLE

11 is in the sequence since it is 3+8 but no other sum of two distinct terms.

PROG

(PARI) Vec(x*(2*x^10+x^8+x^7+2*x^6+x^5+x^4+x^3+x^2+x+1)/((x-1)^2*(x+1)*(x^2+1)) + O(x^100)) \\ Colin Barker, Feb 27 2015

CROSSREFS

Cf. A002858, A033627, A060469, A060470, A060471, A060472.

Virtually identical to A003662.

Sequence in context: A023024 A018362 A033056 * A080329 A002858 A211522

Adjacent sequences:  A060466 A060467 A060468 * A060470 A060471 A060472

KEYWORD

nonn,easy

AUTHOR

Henry Bottomley, Mar 15 2001

STATUS

approved

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Last modified July 22 10:34 EDT 2019. Contains 325219 sequences. (Running on oeis4.)