A330670 Squares of primes congruent to 1 (mod 30).

121, 361, 841, 961, 1681, 3481, 3721, 5041, 6241, 7921, 10201, 11881, 17161, 19321, 22201, 22801, 32041, 32761, 36481, 39601, 44521, 52441, 57121, 58081, 63001, 72361, 73441, 78961, 96721, 109561, 121801, 128881, 143641, 151321, 160801, 167281, 175561, 177241, 185761

Offset

1,1

Comments

Sequence lists squares of prime numbers that end in 1 or 9.

Links

Table of n, a(n) for n=1..39.

Example

Prime 11*11=121 and 19*19=361; 121 and 361 are terms of this sequence.
Prime 13*13=169 and 17*17=289; 169 and 289 are not terms of this sequence.

Maple

seq(ifelse(isprime(n) and (modp(n^2, 30) = 1), n^2, NULL), n = 2..420); # Peter Luschny, Nov 10 2025

Mathematica

Select[Range[360], PrimeQ[#] && Mod[#^2, 30] == 1 &]^2 (* Amiram Eldar, Dec 28 2019 *)

Prog

(PARI) isok(m) = issquare(m) && isprime(sqrtint(m)) && ((m % 30) == 1); \\ Michel Marcus, Dec 26 2019

Crossrefs

Intersection of A001248 and A128470.

Sequence in context: A216166 A208242 A167721 * A253321 A253328 A257035

Adjacent sequences: A330667 A330668 A330669 * A330671 A330672 A330673

Keyword

nonn

Author

Harry E. Neel, Dec 24 2019

Extensions

a(19) corrected by Georg Fischer, Nov 10 2025

a(35) corrected by Michel Marcus, Nov 10 2025

Status

approved