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 A257930 Primes equal to the sum of the prime factors, with multiplicity, of the previous k numbers, for some k. 4
 23, 269, 1049, 1277, 8869951, 972928919, 74885169679 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Values of k are 2, 5, 4, 12, 12, 19, 37, ... a(8) > 10^12. - Giovanni Resta, May 15 2015 Subsequence of prime terms of A257976. - Robert G. Wilson v, May 19 2015 LINKS Table of n, a(n) for n=1..7. EXAMPLE For 23, consider the prime factors of the previous 2 numbers, 21, 22: 3, 7; 2, 11. Their sum is 3 + 7 + 2 + 11 = 23. For 269, consider the prime factors of the previous 5 numbers, 264, 265, 266, 267, 268: 2, 2, 2, 3, 11; 5, 53; 2, 7, 19; 3, 89; 2, 2, 67. Their sum is 2 + 2 + 2 + 3 + 11 + 5 + 53 + 2 + 7 + 19 + 3 + 89 + 2 + 2 + 67 = 269. MAPLE with(numtheory): P:= proc(q) local a, d, j, k, n; for n from 3 to q do if isprime(n) then a:=0; k:=0; while a=n, return(n==s && isprime(n)))) \\ Charles R Greathouse IV, May 15 2015 CROSSREFS Cf. A257367, A257524. Sequence in context: A002681 A240876 A142220 * A142027 A161523 A161930 Adjacent sequences: A257927 A257928 A257929 * A257931 A257932 A257933 KEYWORD nonn,more AUTHOR Paolo P. Lava, May 13 2015 EXTENSIONS a(6)-a(7) from Giovanni Resta, May 15 2015 STATUS approved

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Last modified December 11 02:45 EST 2023. Contains 367717 sequences. (Running on oeis4.)