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 A324699 Lexicographically earliest sequence of positive integers whose prime indices minus 1 already belong to the sequence. 12
 1, 3, 7, 9, 19, 21, 27, 29, 49, 57, 63, 71, 79, 81, 87, 107, 113, 133, 147, 171, 189, 203, 213, 229, 237, 243, 261, 271, 311, 321, 339, 343, 359, 361, 399, 409, 421, 441, 457, 497, 513, 551, 553, 567, 593, 609, 619, 639, 687, 711, 729, 749, 757, 783, 791, 813 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 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. LINKS Table of n, a(n) for n=1..56. FORMULA a(n) = A306719(n) - 1. EXAMPLE The sequence of terms together with their prime indices begins: 1: {} 3: {2} 7: {4} 9: {2,2} 19: {8} 21: {2,4} 27: {2,2,2} 29: {10} 49: {4,4} 57: {2,8} 63: {2,2,4} 71: {20} 79: {22} 81: {2,2,2,2} 87: {2,10} 107: {28} 113: {30} 133: {4,8} 147: {2,4,4} 171: {2,2,8} 189: {2,2,2,4} MATHEMATICA aQ[n_]:=Switch[n, 0, False, 1, True, _, And@@Cases[FactorInteger[n], {p_, k_}:>aQ[PrimePi[p]-1]]]; Select[Range[100], aQ] CROSSREFS Prime indices are A306719. Cf. A000002, A000720, A001222, A001462, A007097, A055396, A061395, A079000, A079254, A109298, A112798, A276625, A277098, A304360, A306719. Cf. A324694, A324695, A324696, A324697, A324698, A324700, A324701, A324702, A324703, A324704, A324705. Sequence in context: A031273 A140118 A191106 * A110674 A003528 A032913 Adjacent sequences: A324696 A324697 A324698 * A324700 A324701 A324702 KEYWORD nonn AUTHOR Gus Wiseman, Mar 10 2019 STATUS approved

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Last modified November 30 02:35 EST 2023. Contains 367452 sequences. (Running on oeis4.)