A251240 Indices of squares of primes in A098550.

4, 5, 11, 40, 124, 187, 273, 313, 505, 747, 751, 1280, 1478, 1563, 1841, 2386, 3130, 3134, 4196, 4493, 4497, 5455, 6002, 6877, 8158, 9047, 9276, 10190, 10194, 11157, 14182, 15086, 16762, 16766, 19758, 20051, 21749, 23435, 24601, 26398, 28655, 28659, 32636

Offset

1,1

Comments

A098550(a(n)) = A001248(n);

A062799(A098550(a(n))) = 2.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..175

Prog

(Haskell)
a251240 n = a251240_list !! (n-1)
a251240_list = filter ((== 2) . a062799 . fromIntegral . a098550) [1..]
(Python)
from gmpy2 import gcd, is_square, is_prime, isqrt
A251240_list, l1, l2, s, b = [], 3, 2, 4, {}
for n in range(4, 10**4):
....i = s
....while True:
........if not i in b and gcd(i, l1) == 1 and gcd(i, l2) > 1:
............l2, l1, b[i] = l1, i, 1
............while s in b:
................b.pop(s)
................s += 1
............if is_square(i) and is_prime(isqrt(i)):
................A251240_list.append(n)
............break
........i += 1 # Chai Wah Wu, Dec 06 2014

Crossrefs

Cf. A098550, A001248, A062799, subsequence of A251241.

Sequence in context: A109503 A304224 A304135 * A361529 A305041 A316731

Adjacent sequences: A251237 A251238 A251239 * A251241 A251242 A251243

Keyword

nonn

Author

Reinhard Zumkeller, Dec 02 2014

Status

approved