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 A138383 If prime(i) = i-th prime, a(n) = prime(n)+1 + prime(n)+2 + ... + prime(n+1). a(0) = 3 by convention. 1
 3, 3, 9, 13, 38, 25, 62, 37, 86, 159, 61, 207, 158, 85, 182, 303, 339, 121, 387, 278, 145, 459, 326, 519, 748, 398, 205, 422, 217, 446, 1687, 518, 807, 277, 1445, 301, 927, 963, 662, 1023, 1059, 361, 1865, 385, 782, 397, 2466, 2610, 902, 457, 926, 1419, 481, 2465, 1527 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS First differences of A034953 for n > 0. - Gionata Neri, May 17 2015 LINKS FORMULA a(n) = (prime(n+1)-prime(n))*(prime(n+1)+prime(n)+1)/2 for n >= 1. - N. J. A. Sloane, May 08 2008 EXAMPLE 3 = 1 + 2; 3 = 3; 9 = 4 + 5; 13 = 6 + 7; 38 = 8 + 9 + 10 + 11; ... MAPLE 3, seq((ithprime(n+1)-ithprime(n))*(ithprime(n+1)+ithprime(n)+1)/2, n=1..100); # Robert Israel, May 17 2015 MATHEMATICA Join[{3}, Table[(Prime[n+1] - Prime[n]) (Prime[n+1] + Prime[n] + 1)/2, {n, 60}]] (* Vincenzo Librandi, May 18 2015 *) Join[{3}, (#[[2]]-#[[1]]) (Total[#]+1)/2&/@Partition[Prime[Range[ 60]], 2, 1]] (* Harvey P. Dale, Oct 27 2020 *) PROG (MAGMA) [3] cat [(NthPrime(n+1) - NthPrime(n))*(NthPrime(n+1) + NthPrime(n)+1)/2: n in [1..60]]; // Vincenzo Librandi, May 18 2015 CROSSREFS Cf. A000040. Sequence in context: A183811 A303640 A091328 * A052436 A243790 A267296 Adjacent sequences:  A138380 A138381 A138382 * A138384 A138385 A138386 KEYWORD nonn,easy AUTHOR Odimar Fabeny, May 08 2008 STATUS approved

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Last modified April 13 18:53 EDT 2021. Contains 342939 sequences. (Running on oeis4.)