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A298301 The first of three consecutive heptagonal numbers the sum of which is equal to the sum of three consecutive primes. 4
7, 874, 7209, 15484, 16687, 23863, 68641, 98704, 122877, 239785, 373842, 455182, 498852, 523723, 601966, 652036, 769230, 777573, 1003939, 1019844, 1121245, 1189215, 1203049, 1420159, 1484946, 1594804, 1606807, 1687977, 1804975, 2292973, 2533612, 3012363 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000 (n = 1..100 from Colin Barker)

EXAMPLE

7 is in the sequence because 7+18+34 (consecutive hexagonal numbers) = 59 = 17+19+23 (consecutive primes).

PROG

(PARI) L=List(); forprime(p=2, 2000000, q=nextprime(p+1); r=nextprime(q+1); t=p+q+r; if(issquare(120*t-519, &sq) && (sq-21)%30==0, u=(sq-21)\30; listput(L, (5*u^2-3*u)/2))); Vec(L)

CROSSREFS

Cf. A000040, A000566, A054643, A298073, A298168, A298169, A298222, A298223, A298250, A298251, A298272, A298273, A298302.

Sequence in context: A087350 A308296 A193342 * A332187 A093171 A330295

Adjacent sequences: A298298 A298299 A298300 * A298302 A298303 A298304

KEYWORD

nonn

AUTHOR

Colin Barker, Jan 16 2018

STATUS

approved

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Last modified February 1 20:21 EST 2023. Contains 359995 sequences. (Running on oeis4.)