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 A341661 Primes p such that p^4 - 1 has fewer than 160 divisors. 1
 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 59, 61, 71, 79, 101 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For all primes p > 101, p^4 - 1 has at least A309906(4)=160 divisors. LINKS EXAMPLE p = n a(n) p^4 - 1 factorization of p^4 - 1 tau(p^4 - 1) -- ---- --------- ------------------------- ------------ 1 2 15 3 * 5 4 2 3 80 2^4 * 5 10 3 5 624 2^4 * 3 * 13 20 4 7 2400 2^5 * 3 * 5^2 36 5 11 14640 2^4 * 3 * 5 * 61 40 6 13 28560 2^4 * 3 * 5 * 7 * 17 80 7 17 83520 2^6 * 3^2 * 5 * 29 84 8 19 130320 2^4 * 3^2 * 5 * 181 60 9 23 279840 2^5 * 3 * 5 * 11 * 53 96 10 29 707280 2^4 * 3 * 5 * 7 * 421 80 11 31 923520 2^7 * 3 * 5 * 13 * 37 128 12 37 1874160 2^4 * 3^2 * 5 * 19 * 137 120 13 41 2825760 2^5 * 3 * 5 * 7 * 29^2 144 14 59 12117360 2^4 * 3 * 5 * 29 * 1741 80 15 61 13845840 2^4 * 3 * 5 * 31 * 1861 80 16 71 25411680 2^5 * 3^2 * 5 * 7 * 2521 144 17 79 38950080 2^6 * 3 * 5 * 13 * 3121 112 18 101 104060400 2^4 * 3 * 5^2 * 17 * 5101 120 MATHEMATICA Select[Range[101], PrimeQ[#] && DivisorSigma[0, #^4 - 1] < 160 &] (* Amiram Eldar, Feb 26 2021 *) CROSSREFS Cf. A000005, A000040, A309906, A341656. Sequence in context: A109611 A181325 A078133 * A268513 A256484 A238242 Adjacent sequences: A341658 A341659 A341660 * A341662 A341663 A341664 KEYWORD nonn,fini,full AUTHOR Jon E. Schoenfield, Feb 26 2021 STATUS approved

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Last modified March 28 13:18 EDT 2023. Contains 361585 sequences. (Running on oeis4.)