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 A178382 Primes that are in classes k+ and k- for some k in the Erdős-Selfridge classification of primes. 0
 2, 3, 5, 7, 17, 29, 41, 43, 61, 79, 101, 131, 137, 149, 173, 197, 211, 223, 227, 229, 233, 239, 241, 251, 271, 281, 293, 307, 311, 331, 353, 397, 439, 449, 463, 523, 569, 593, 607, 641, 683, 691, 727, 733, 751, 761, 787, 821, 853, 859, 919, 947, 953, 983, 1031 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The first five terms are the only primes in both class 1+ and class 1-. The Mathematica program assigns 2 and 3 to class 0 in order to simplify the algorithm; they are actually in classes 1- and 1+. LINKS Table of n, a(n) for n=1..55. FORMULA Prime(n) such that A126433(n) = A126805(n). MATHEMATICA classp[2]=0; classp[3]=0; SetAttributes[classp, Listable]; classp[p_] := classp[p] = 1+Max@@classp[First/@FactorInteger[p+1]]; classm[2]=0; classm[3]=0; SetAttributes[classm, Listable]; classm[p_] := classm[p] = 1+Max@@classm[First/@FactorInteger[p-1]]; Select[Prime[Range[1000]], classp[ # ]==classm[ # ]&] CROSSREFS Sequence in context: A107439 A262836 A356475 * A360591 A289757 A030480 Adjacent sequences: A178379 A178380 A178381 * A178383 A178384 A178385 KEYWORD nonn AUTHOR T. D. Noe, May 26 2010 STATUS approved

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Last modified June 12 14:48 EDT 2024. Contains 373331 sequences. (Running on oeis4.)