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A180617
Sum of divisors of the product of two consecutive primes.
3
12, 24, 48, 96, 168, 252, 360, 480, 720, 960, 1216, 1596, 1848, 2112, 2592, 3240, 3720, 4216, 4896, 5328, 5920, 6720, 7560, 8820, 9996, 10608, 11232, 11880, 12540, 14592, 16896, 18216, 19320, 21000, 22800, 24016, 25912, 27552, 29232, 31320, 32760, 34944, 37248, 38412
OFFSET
1,1
FORMULA
a(n) = A000203(A006094(n)). - Omar E. Pol, Dec 08 2019
a(n) = A006094(n) + A001043(n) + 1. - Metin Sariyar, Dec 08 2019
a(n) = A126199(n) + 1 (after above formula). - Omar E. Pol, Dec 08 2019
EXAMPLE
a(1) = sigma(2*3) = 12, a(2) = sigma(3*5) = 24.
MATHEMATICA
DivisorSigma[1, #]&/@(Times@@@Partition[Prime[Range[50]], 2, 1]) (* Harvey P. Dale, Apr 04 2015 *)
Table[Prime[n]*Prime[n+1]+Prime[n]+Prime[n+1]+1, {n, 1, 30}] (* Metin Sariyar, Dec 08 2019 *)
PROG
(PARI) for (n=1, 10, i=prod(x=n, n+1, prime(x)); p=sigma(i); print1(p, ", "); )
(PARI) a(n)=my(p=prime(n)); (p+1)*(nextprime(p+1)+1) \\ Charles R Greathouse IV, Feb 16 2015
(Magma) [(1+NthPrime(n))*(1+NthPrime(n+1)): n in [1..50]]; // Vincenzo Librandi, Feb 16 2015
CROSSREFS
A distant relative of A054640.
Sequence in context: A367105 A270257 A367361 * A081808 A369798 A260261
KEYWORD
nonn
AUTHOR
Thomas Kellar, Sep 12 2010
EXTENSIONS
More terms from Vincenzo Librandi, Feb 16 2015
Name simplified by Omar E. Pol, Dec 08 2019
STATUS
approved