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A078706
a(n) = smallest integer >=a(n-1) such that sum of first n terms is prime.
2
2, 3, 6, 6, 6, 6, 8, 10, 12, 12, 12, 14, 16, 18, 18, 18, 24, 32, 34, 36, 38, 42, 46, 48, 54, 56, 64, 68, 78, 90, 90, 94, 102, 114, 122, 124, 134, 144, 148, 150, 152, 160, 168, 170, 178, 182, 190, 192, 200, 216, 220, 222, 234, 234, 234, 246, 260, 264, 268, 270, 278, 280
OFFSET
1,1
LINKS
EXAMPLE
a(1)=2, the first prime. The smallest integer >=2 that yields a prime when added to 2 is 3, so a(2)=3. The smallest integer >=3 that yields a prime when added to 2+3 is 6 so a(3)=6.
MATHEMATICA
s = 0; NestList[(s += #; NextPrime[s + # - 1] - s) &, 2, 61] (* Ivan Neretin, May 14 2015 *)
nxt[{t_, a_}]:=Module[{k=a}, While[CompositeQ[t+k], k++]; {t+k, k}]; NestList[nxt, {2, 2}, 70][[;; , 2]] (* Harvey P. Dale, Sep 01 2024 *)
CROSSREFS
Cf. A051935.
Sequence in context: A290223 A274213 A350315 * A077082 A333936 A193896
KEYWORD
easy,nonn
AUTHOR
Neil Fernandez, Dec 18 2002
STATUS
approved