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A321337 a(n) is the least number with n factorizations into S-primes (numbers 4k+1 with no proper divisors > 1 of form 4m+1). 1
1, 441, 4389, 39501, 53361, 92169, 829521, 1935549, 302841, 2725569, 3041577, 27374193, 853577109, 7682193981, 3129357, 6359661, 19263321, 234201429, 230639102001, 437200389130923862144165773, 1341335457, 12072019113, 23318757, 1201975929, 28164213, 253477917, 4918230009, 101711843982441 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
It suffices to check only numbers with all prime factors congruent to 3 mod 4 and continuous, nonincreasing prime exponents (i.e., members of the analog of A025487 with respect to primes congruent to 3 mod 4).
LINKS
EXAMPLE
a(4) = 39501 can be factored into S-primes (A057948) in 4 distinct ways: 9 * 21 * 209, 9 * 33 * 133, 9 * 57 * 77, or 21 * 33 * 57, and it is the smallest number with this property.
CROSSREFS
Cf. A054520, A057948 (S-primes), A057949 (numbers with multiple factorizations into S-primes).
Sequence in context: A202400 A014793 A264305 * A206467 A264262 A232003
KEYWORD
nonn
AUTHOR
Charlie Neder, Nov 05 2018
EXTENSIONS
a(13) corrected by David A. Corneth, Nov 10 2018
More terms from WG Zeist, Jan 09 2019
STATUS
approved

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Last modified March 2 20:41 EST 2024. Contains 370498 sequences. (Running on oeis4.)