A087521 - OEIS

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A087521

Smallest prime p such that the prime signature of p+1 has not occurred earlier.

2, 3, 5, 7, 11, 23, 29, 31, 47, 59, 71, 127, 167, 179, 191, 223, 239, 359, 383, 389, 419, 431, 479, 719, 839, 863, 971, 1151, 1259, 1279, 1439, 1511, 2111, 2309, 2591, 2687, 2699, 2879, 3023, 3119, 3359, 3583, 3779, 5039, 5119, 5399, 6047, 6143, 6299, 6719

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..1200

Index entries for sequences related to prime signature

MATHEMATICA

sig[n_] := Sort @ FactorInteger[n][[;; , 2]]; seq = {}; sigs = {}; Do[If[PrimeQ[p] && !MemberQ[sigs, (s = sig[p + 1])], AppendTo[seq, p]; AppendTo[sigs, s]], {p, 2, 7000}]; seq (* Amiram Eldar, Dec 30 2020 *)

CROSSREFS

Cf. A087520.

Sequence in context: A284146 A376236 A317479 * A078403 A129945 A046704

Adjacent sequences: A087518 A087519 A087520 * A087522 A087523 A087524

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Sep 11 2003

EXTENSIONS

Edited by Ray Chandler, Sep 14 2003

Offset corrected by Amiram Eldar, Dec 30 2020

STATUS

approved