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 A270536 a(1) = 0; a(n) is the sum of m < n for which a(m) + n is not prime. 2
 0, 0, 0, 6, 0, 15, 6, 22, 28, 45, 33, 66, 35, 64, 74, 104, 102, 140, 129, 160, 182, 196, 170, 263, 241, 285, 257, 281, 319, 329, 372, 423, 414, 460, 491, 537, 520, 582, 623, 647, 724, 836, 731, 772, 817, 947, 887, 1062, 879, 834, 1076 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Peter Kagey, Table of n, a(n) for n = 1..1000 EXAMPLE a(1) = 0. a(2) = 0 because 2 + a(1) is prime. a(3) = 0 because 3 + a(i) is prime for 1 <= i <= 2. a(4) = 6 because 4 + a(1), 4 + a(2), and 4 + a(3) are nonprime; 1 + 2 + 3 = 6. a(5) = 0 because 5 + a(i) is prime for 1 <= i <= 4. PROG (Java) public static int[] sequenceD(int n) {     int[] terms = new int[n];     terms[0] = 0;     terms[1] = 0;     for (int i = 2; i < n; i++) {         int count = 0;         for (int j = 1; j < i; j++) {             if (!prime(terms[j] + i)) {                 count = count + j;             }         }         terms[i] = count;     }     return terms; } (PARI) lista(nn) = {va = vector(nn); print1(va[1], ", "); for (n=2, nn, va[n] = sum(k=1, n-1, k*(! isprime(n+va[k]))); print1(va[n], ", "); ); } \\ Michel Marcus, Mar 28 2016 CROSSREFS Cf. A270654, which is the sum of m < n for which a(m) + n is prime. Sequence in context: A175567 A069828 A340951 * A278712 A057401 A308236 Adjacent sequences:  A270533 A270534 A270535 * A270537 A270538 A270539 KEYWORD easy,nonn AUTHOR Alec Jones, Mar 28 2016 STATUS approved

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Last modified August 8 21:55 EDT 2022. Contains 356016 sequences. (Running on oeis4.)