A357219 Primes of the form T(p) - 2 where T(p) is the triangular number (A000217) with prime index p in A357218.

13, 89, 151, 433, 701, 859, 1429, 1889, 2699, 4003, 4751, 11173, 12401, 18719, 19501, 27259, 33151, 36313, 38501, 39619, 49139, 56951, 75853, 80599, 83843, 104651, 129793, 135979, 146609, 188189, 205759, 226799, 246049, 318001, 367651, 385001, 388519, 431983, 454579

Offset

1,1

References

David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Revised Edition, Penguin Books, London, England, 1997, entry 496, page 142.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000217(A357218(n))-2.

Maple

f:= n -> n*(n+1)/2-2:
select(isprime, map(f, [seq(ithprime(i), i=1..200)])); # Robert Israel, Sep 20 2022

Mathematica

Select[(#*(# + 1)/2 - 2) & /@ Prime[Range[165]], PrimeQ] (* Amiram Eldar, Sep 18 2022 *)

Prog

(PARI) isok(p) = my(q); isprime(p) && ispolygonal(p+2, 3, &q) && isprime(q); \\ Michel Marcus, Sep 19 2022

Crossrefs

Cf. A000217, A357218.

Subsequence of A124199.

Sequence in context: A141878 A132260 A181508 * A082099 A282858 A268746

Adjacent sequences: A357216 A357217 A357218 * A357220 A357221 A357222

Keyword

nonn

Author

Bernard Schott, Sep 18 2022

Extensions

More terms from David A. Corneth, Sep 18 2022

Status

approved