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 A296440 a(1) = 2, a(2) = a(3) = 3, a(4) = 4, a(5) = a(6) = 6; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3))  for n > 6. 6
 2, 3, 3, 4, 6, 6, 7, 8, 8, 9, 9, 10, 11, 13, 13, 12, 14, 16, 16, 14, 19, 17, 18, 19, 21, 21, 20, 22, 23, 24, 23, 24, 25, 26, 26, 27, 27, 28, 29, 30, 30, 31, 32, 34, 33, 34, 35, 37, 36, 37, 39, 36, 39, 42, 39, 41, 41, 44, 45, 41, 40, 50, 46, 48, 43, 48, 51, 49, 49, 54, 48, 53, 51, 58, 50, 58, 52, 57, 56, 59, 57, 60, 58 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Conjecture: Sequence is infinite. LINKS Altug Alkan, Table of n, a(n) for n = 1..10000 Altug Alkan, Scatterplot of a(n)-2*n/3 Hans Havermann, Scatterplot of a(n) for n <= 10^7 MAPLE a:= proc(n) option remember; procname(n-procname(n-1))+procname(n-procname(n-2))+procname(n-procname(n-3)) end proc: a(1):= 2: a(2):= 3: a(3):= 3: a(4):= 4: a(5):= 6: a(6):= 6: map(a, [\$1..100]); # Robert Israel, Dec 12 2017 MATHEMATICA a[n_] := a[n] = If[n<7, {2, 3, 3, 4, 6, 6}[[n]], a[n - a[n-1]] + a[n - a[n-2]] + a[n - a[n-3]]]; Array[a, 83] (* Giovanni Resta, Dec 13 2017 *) PROG (PARI) q=vector(10^5); q[1]=2; q[2]=3; q[3]=3; q[4]=4; q[5]=6; q[6]=6; for(n=7, #q, q[n] = q[n-q[n-1]]+q[n-q[n-2]]+q[n-q[n-3]]); q (Scheme, with memoization-macro definec) (definec (A296440 n) (cond ((= 1 n) 2) ((<= n 3) 3) ((= 4 n) 4) ((<= n 6) 6) (else (+ (A296440 (- n (A296440 (- n 1)))) (A296440 (- n (A296440 (- n 2)))) (A296440 (- n (A296440 (- n 3)))))))) ;; Antti Karttunen, Dec 13 2017 CROSSREFS Cf. A005185, A278055, A284644, A292351. Sequence in context: A106464 A093003 A118096 * A181692 A145806 A100989 Adjacent sequences:  A296437 A296438 A296439 * A296441 A296442 A296443 KEYWORD nonn,look AUTHOR Altug Alkan, Dec 12 2017 STATUS approved

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Last modified September 21 19:57 EDT 2020. Contains 337273 sequences. (Running on oeis4.)