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A087402
a(n) is the smallest repdigit > 10 such that Sum_{i=0..n} a(i) is prime.
1
11, 222, 44, 222, 22, 66, 44, 22, 66, 222, 222, 66, 222, 888, 44, 666, 88, 44, 22, 888, 66, 44, 88, 444, 66, 222, 66, 66, 44, 222, 22, 66, 66, 66, 44, 66, 888, 22, 44, 88, 66, 222, 444, 66, 2222, 22, 666, 2222, 22, 66, 44, 66, 22, 66, 222, 222, 6666, 44, 22, 66, 444, 66
OFFSET
0,1
COMMENTS
The total of the first 992 terms (from a(0) to a(991)) is a prime with 1247 digits. The largest term among the first 992 terms is a(920), which also has 1247 digits. If a(992) exists, it has more than 1251 digits. - Harvey P. Dale, Sep 03 2023
LINKS
EXAMPLE
11, 11+222=233, 11+222+44=277 etc. are all prime.
MATHEMATICA
nxt[{t_, n_}]:=Module[{tbl=LinearRecurrence[{0, 0, 0, 11, 0, 0, 0, -10}, {22, 44, 66, 88, 222, 444, 666, 888}, 20], c}, c= SelectFirst[tbl, PrimeQ[t+#]&]; {t+c, c}]; NestList[nxt, {11, 11}, 70][[;; , 2]] (* Harvey P. Dale, Sep 03 2023 *)
CROSSREFS
Sequence in context: A055411 A341491 A064093 * A048377 A192686 A323416
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Sep 10 2003
EXTENSIONS
More terms from Ray Chandler and Vladeta Jovovic, Sep 22 2003
New name from David A. Corneth, Sep 03 2023
STATUS
approved