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A114991 Primes of the form 2^a * 3^b * 5^c + 1 for positive a, b, c. 1
31, 61, 151, 181, 241, 271, 541, 601, 751, 811, 1201, 1621, 1801, 2161, 2251, 3001, 4051, 4801, 4861, 6481, 7681, 8101, 8641, 9001, 9601, 9721, 11251, 14401, 15361, 19441, 21601, 21871, 22501, 23041, 24001, 32401, 33751, 36451, 37501, 43201, 54001, 57601, 58321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Compare with A005109 "Class 1- (or Pierpont) primes: primes of the form 2^t*3^u + 1." One might call this new sequence "(2,3,5)-Pierpont) primes."

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

FORMULA

(For a,b,c>0, 2^a * 3^b * 5^c + 1 IFF prime}. (For a,b,c>0, 2^a * 3^b * 5^c + 1 IFF in A000040}.

EXAMPLE

a(1) = 31 = 2^1 * 3^1 * 5^1 + 1.

a(2) = 61 = 2^2 * 3^1 * 5^1 + 1.

a(3) = 151 = 2^1 * 3^1 * 5^2 + 1.

a(4) = 181 = 2^2 * 3^2 * 5^1 + 1.

Values include 30000001 = 2^7 * 3^1 * 5^7 + 1, 90000000001 = 2^9 * 3^2 * 5^9 + 1.

CROSSREFS

Cf. A000040, A005109, A030430.

Cf. A143207

Sequence in context: A132230 A136066 A282326 * A225874 A139892 A088464

Adjacent sequences:  A114988 A114989 A114990 * A114992 A114993 A114994

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Feb 22 2006

STATUS

approved

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Last modified June 4 08:18 EDT 2020. Contains 334825 sequences. (Running on oeis4.)