login
This site is supported by donations to The OEIS Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A114023 Squares of the form semiprime(n) + n-th triangular number. 0
4, 16, 100, 144, 33489, 82369, 41088506209, 95056905969, 196978855329, 4901432910724, 6047212155664, 26601838343809, 247869502464123136 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(14) > 10^18. - Donovan Johnson, Jun 04 2013

LINKS

Table of n, a(n) for n=1..13.

FORMULA

a(n) = semiprime(k) + k(k+1)/2 when this is a square.

PROG

(PARI) lista(nn) = {n = -1; for (i=1, nn, if (bigomega(i) == 2, n++; if (issquare(sq=i + n*(n+1)/2), print1(sq, ", ")); ); ); } \\ Michel Marcus, Jun 03 2013

CROSSREFS

Cf. A000217, A111440, A112662.

Sequence in context: A209299 A091040 A029985 * A145823 A121142 A318693

Adjacent sequences:  A114020 A114021 A114022 * A114024 A114025 A114026

KEYWORD

nonn

AUTHOR

Giovanni Teofilatto, Feb 01 2006

EXTENSIONS

More terms from Michel Marcus, Jun 03 2013

a(7)-a(13) from Donovan Johnson, Jun 04 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 18 20:57 EST 2019. Contains 319282 sequences. (Running on oeis4.)