A261888 - OEIS

A261888

Positive integers n such that there is no triple of primes (p, q, r) satisfying p+q^2+r^3=n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16, 18, 21, 26, 27, 32, 37, 45, 51, 61, 66, 82, 108, 127, 178, 186, 192, 234, 252, 276, 306, 332, 336, 351, 402, 468, 582, 606, 612, 622, 642, 666, 702, 712, 738, 762, 798, 816, 822, 864, 882, 906, 930, 996, 1018, 1032

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..59.

EXAMPLE

For p=2, p+p^2+p^3 = 14 = A181149(1), so 14 is the first value not to be in the sequence.

PROG

(PARI) nbt(n) = {nb = 0; forprime(p=2, n, forprime(q=2, n, if (p+q^2 > n, break); forprime(r=2, n, if (p+q^2+r^3 > n, break); if (p+q^2+r^3 == n, nb++); ); ); ); nb; }

isok(n) = nbt(n)==0;

CROSSREFS

Cf. A181149, A261887.

Sequence in context: A283657 A053432 A349999 * A154125 A106039 A151767

Adjacent sequences: A261885 A261886 A261887 * A261889 A261890 A261891

KEYWORD

nonn

AUTHOR

Michel Marcus, Sep 05 2015

STATUS

approved