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A026472 {3, 7} together with the numbers congruent to {1, 2} mod 12. 3
1, 2, 3, 7, 13, 14, 25, 26, 37, 38, 49, 50, 61, 62, 73, 74, 85, 86, 97, 98, 109, 110, 121, 122, 133, 134, 145, 146, 157, 158, 169, 170, 181, 182, 193, 194, 205, 206, 217, 218, 229, 230, 241, 242, 253, 254, 265, 266, 277, 278, 289, 290, 301, 302, 313, 314 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The old definition of this sequence was "a(n) = least positive integer > a(n-1) and not equal to a(i)+a(j)+a(k) for 1<=i<=j<=k<=n". However, Ralf Stephan observes that this does not fit the terms shown. The present definition (due to Stephan) has been adopted as a temporary solution. - N. J. A. Sloane, Nov 24 2004

Regarding the old definition, see Comments at A047239. - Clark Kimberling, Oct 09 2019

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..10000

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

FORMULA

From Colin Barker, Oct 10 2019: (Start)

G.f.: x*(1 + x + 3*x^3 + 5*x^4 - 3*x^5 + 5*x^6) / ((1 - x)^2*(1 + x)).

a(n) = a(n-1) + a(n-2) - a(n-3) for n>6.

a(n) = -(39/2) - (5*(-1)^n)/2 + 6*n for n>4.

(End)

MATHEMATICA

p = {1, 2, 3, 7}; r = 12 Range[200]; Union[p, 1 + r, 2 + r] (* Clark Kimberling, Oct 10 2019 *)

PROG

(PARI) Vec(x*(1 + x + 3*x^3 + 5*x^4 - 3*x^5 + 5*x^6) / ((1 - x)^2*(1 + x)) + O(x^40)) \\ Colin Barker, Oct 20 2019

CROSSREFS

Cf. A026476, A026474.

Sequence in context: A081256 A084955 A273056 * A286176 A318401 A322703

Adjacent sequences:  A026469 A026470 A026471 * A026473 A026474 A026475

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

More terms

STATUS

approved

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Last modified April 3 04:21 EDT 2020. Contains 333195 sequences. (Running on oeis4.)