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 A324702 Lexicographically earliest sequence containing 2 and all positive integers > 1 whose prime indices minus 1 already belong to the sequence. 12
 2, 5, 13, 25, 43, 65, 101, 125, 169, 193, 215, 317, 325, 505, 557, 559, 625, 701, 845, 965, 1013, 1075, 1181, 1313, 1321, 1585, 1625, 1849, 2111, 2161, 2197, 2509, 2525, 2785, 2795, 3125, 3505, 3617, 4049, 4057, 4121, 4225, 4343, 4639, 4825, 5065, 5297, 5375 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A self-describing sequence, similar to A304360. 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 2 and numbers whose prime indices belong to A324703. LINKS Table of n, a(n) for n=1..48. FORMULA a(n) = A324703(n) - 1. EXAMPLE The sequence of terms together with their prime indices begins: 2: {1} 5: {3} 13: {6} 25: {3,3} 43: {14} 65: {3,6} 101: {26} 125: {3,3,3} 169: {6,6} 193: {44} 215: {3,14} 317: {66} 325: {3,3,6} 505: {3,26} 557: {102} 559: {6,14} 625: {3,3,3,3} 701: {126} 845: {3,6,6} 965: {3,44} MATHEMATICA aQ[n_]:=Switch[n, 0, False, 1, False, 2, True, _, And@@Cases[FactorInteger[n], {p_, k_}:>aQ[PrimePi[p]-1]]]; Select[Range[100], aQ] CROSSREFS Prime indices > 1 are A324703. Cf. A000002, A000720, A001222, A001462, A007097, A045965, A055396, A061395, A064989, A079000, A079254, A109298, A112798, A276625, A277098, A304360. Cf. A324694, A324695, A324696, A324697, A324698, A324699, A324700, A324701, A324704, A324705. Sequence in context: A362105 A309230 A048871 * A072921 A289529 A087250 Adjacent sequences: A324699 A324700 A324701 * A324703 A324704 A324705 KEYWORD nonn AUTHOR Gus Wiseman, Mar 11 2019 STATUS approved

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Last modified November 30 02:46 EST 2023. Contains 367452 sequences. (Running on oeis4.)