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A075402 Smallest number such that a(n) + T(n) is a prime, where T(n) is the n-th triangular number. 2
1, 0, 1, 1, 2, 2, 1, 1, 2, 4, 1, 1, 6, 2, 7, 1, 4, 2, 1, 1, 2, 4, 1, 7, 6, 2, 1, 3, 4, 2, 3, 13, 2, 4, 1, 7, 6, 2, 7, 1, 2, 4, 1, 1, 4, 6, 1, 5, 4, 2, 1, 3, 2, 2, 3, 1, 4, 10, 7, 1, 10, 20, 1, 1, 8, 2, 3, 1, 2, 18, 1, 5, 6, 2, 1, 1, 8, 2, 3, 11, 2, 4, 5, 1, 4, 20, 5, 1, 2, 4, 15, 5, 2, 16, 1, 1, 6, 10, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

0 occurs only once in this sequence.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

If[PrimeQ[#], #, NextPrime[#]]-#&/@Accumulate[Range[100]] (* Harvey P. Dale, Nov 21 2012 *)

PROG

(PARI) for(n=1, 100, a=n*(n+1)/2:print1(nextprime(a)-a", "))

CROSSREFS

Cf. A075403.

Sequence in context: A240168 A199204 A262750 * A276696 A220777 A088855

Adjacent sequences:  A075399 A075400 A075401 * A075403 A075404 A075405

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Sep 23 2002

EXTENSIONS

Corrected and extended by Ralf Stephan, Mar 19 2003

STATUS

approved

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Last modified October 18 16:59 EDT 2018. Contains 316323 sequences. (Running on oeis4.)