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 A324561 Numbers with at least one prime index equal to 0, 1, or 4 modulo 5. 2
 2, 4, 6, 7, 8, 10, 11, 12, 13, 14, 16, 18, 20, 21, 22, 23, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 38, 39, 40, 42, 43, 44, 46, 47, 48, 49, 50, 52, 53, 54, 55, 56, 58, 60, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 76, 77, 78, 80, 82, 84, 86, 87 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798. Also Heinz numbers of the integer partitions counted by A039900. The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k). LINKS Table of n, a(n) for n=1..66. EXAMPLE The sequence of terms together with their prime indices begins: 2: {1} 4: {1,1} 6: {1,2} 7: {4} 8: {1,1,1} 10: {1,3} 11: {5} 12: {1,1,2} 13: {6} 14: {1,4} 16: {1,1,1,1} 18: {1,2,2} 20: {1,1,3} 21: {2,4} 22: {1,5} 23: {9} 24: {1,1,1,2} MAPLE with(numtheory): q:= n-> is(irem(pi(min(factorset(n))), 5) in {0, 1, 4}): select(q, [\$2..100])[]; # Alois P. Heinz, Mar 07 2019 MATHEMATICA Select[Range[100], Intersection[Mod[If[#==1, {}, PrimePi/@First/@FactorInteger[#]], 5], {0, 1, 4}]!={}&] CROSSREFS Cf. A008854, A039900, A055396, A056239, A061395, A106529, A112798. Cf. A324519, A324521, A324522, A324560, A324561, A324562. Sequence in context: A268445 A053663 A376108 * A288258 A075313 A183858 Adjacent sequences: A324558 A324559 A324560 * A324562 A324563 A324564 KEYWORD nonn AUTHOR Gus Wiseman, Mar 06 2019 STATUS approved

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Last modified September 16 07:48 EDT 2024. Contains 375959 sequences. (Running on oeis4.)