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A083744 a(1) = 1; if a(n-1) + n is composite then a(n) = a(n-1) + n, else a(n) = a(n-1). 2
1, 1, 4, 8, 8, 14, 21, 21, 30, 40, 51, 63, 76, 90, 105, 121, 138, 156, 175, 195, 216, 238, 261, 285, 310, 336, 363, 391, 420, 450, 481, 513, 546, 580, 615, 651, 688, 726, 765, 805, 846, 888, 931, 975, 1020, 1066, 1113, 1161, 1210, 1260, 1311, 1363, 1416, 1470 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..10000

MAPLE

a := proc(n) option remember: if n=1 then RETURN(1) fi: if isprime(a(n-1)+n) then RETURN(a(n-1)) else RETURN(a(n-1)+n) fi: end: for n from 1 to 100 do printf(`%d, `, a(n)) od: # James A. Sellers, May 19 2003

MATHEMATICA

a083744[n_] := Block[{i, t = Table[1, {n}]},

  For[i = 2, i < n,

   If[CompositeQ[t[[i - 1]] + i], t[[i]] = t[[i - 1]] + i,

t[[i]] = t[[i - 1]]], i++]; t]; a083744[54] (* Michael De Vlieger, Dec 24 2014 *)

CROSSREFS

Cf. A083743.

Sequence in context: A014198 A316316 A159786 * A255992 A273572 A273779

Adjacent sequences:  A083741 A083742 A083743 * A083745 A083746 A083747

KEYWORD

easy,nonn

AUTHOR

Amarnath Murthy, May 05 2003

EXTENSIONS

More terms from James A. Sellers, May 19 2003

STATUS

approved

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Last modified February 19 20:17 EST 2019. Contains 320328 sequences. (Running on oeis4.)