A030692 Smallest nontrivial extension of n-th cube which is a prime.

11, 83, 271, 641, 1259, 2161, 3433, 51217, 7297, 10007, 13313, 172829, 21977, 27449, 33751, 40961, 49139, 58321, 68597, 800011, 926111, 106487, 1216711, 138241, 156253, 1757617, 196831, 219523, 2438911, 270001, 297911, 327689

Offset

1,1

Comments

Extensions here cannot contain leading 0's, otherwise we would have a(8)=51203. - Sean A. Irvine, Apr 05 2020

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

necp[n_]:=Module[{idn=IntegerDigits[n], k=1}, While[!PrimeQ[ FromDigits[ Join[ idn, IntegerDigits[k]]]], k=k+2]; FromDigits[Join[idn, IntegerDigits[ k]]]]; necp/@(Range[40]^3) (* Harvey P. Dale, Dec 11 2013 *)

Prog

(PARI) a(n) = {my(k=1); while(!isprime(x=eval(concat(Str(n^3), Str(k)))), k++); x; }; \\ Michel Marcus, Apr 07 2020

Crossrefs

Different from A029949.

Cf. A030685 (for squares).

Sequence in context: A123367 A177142 A129388 * A294831 A055369 A016282

Adjacent sequences: A030689 A030690 A030691 * A030693 A030694 A030695

Keyword

nonn,base

Author

Patrick De Geest

Status

approved